Published: May 15, 2025 26 Comments

Strawberry Rhubarb Slab Pie with Pistachio Crumb Topping [Sponsored Post]

This Strawberry Rhubarb Slab Pie has a crunchy pistachio topping made with olive oil which adds a peppery fruity dimension to the topping.

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A slice of strawberry rhubarb slab pie with pistachio crumb topping on a plate. with the remaining pie and a mug of tea behind it.

Last month I had the pleasure of visiting San Luis Obispo, otherwise known as SLO, with my friends at California Grown. I’ve collaborated with California Grown for years, going on farm tours and visiting local producers across the golden state of California. Last year was one of my favorite tours ever, as we had a chance to visit a rhubarb farm and I’m OBSESSED with rhubarb, as evident by my strawberry rhubarb pie, strawberry rhubarb cobbler, strawberry rhubarb buckle cake, strawberry rhubarb galette, strawberry rhubarb syrup, blueberry rhubarb pie, cherry rhubarb crisp, and so many more recipes.

This year’s trip did not involve rhubarb, but it did involve a group of us staying at the iconic Madonna Inn, visiting Pasolivo Olive Oil to do some olive oil tasting (pro tip, slurp it up and expect the peppery burn cough from super fresh olive oil), wine tasting at Hope Family Wines, and visiting FARMstead ED/City Farm SLO, where we learned about their educational program on sustainable practices, multiple ways to compost, and outreach to the community.

Left image is the Madonna Inn sign. Right image is a cow painted with the Madonna Inn signature pink and flowers pattern.

Left image is a hand pour olive oil into sample cups. Right image is an Asian man sipping and sampling one of the olive oils. — _{Left photo by Irvin Lin. Right photo courtesy of CA GROWN/BCMA.}

Left image a goat with his front legs on a salt lick block. Right image is an Asian man holding a head of lettuce on a farm. — _{Left photo by Irvin Lin. Right photo courtesy of CA Grown/BCMA}

But it was the event at Hope On Park that made this one of the best trip yet (even if it didn’t involved rhubarb). There, my friend Becky of Baking the Goods demonstrated how to make an edible centerpiece using California produce using plates and cups that I made for the entire group. I don’t talk about it much, but I have a not-so-secret double life where I do pottery and ceramics. Becky and the folks at California Grown found out and asked if I would be willing to make cake stands for all the participants in this tour. Months of work later, I got the pleasure of seeing all my talented friends use my ceramics to make the most beautiful centerpieces!

Left image is a neon sign that says Hope with four bottles of rose on a table. Right image is an edible centerpiece on a ceramic cake stand. — _{Left photo courtesy of CA GROWN/BCMA. Right photo by Irvin Lin.}

Left image is a woman holding a ceramic cup, demonstrating how to put together an edible centerpiece. Right image is an Asian man holding a ceramic plate with an edible centerpiece on it. — _{Left photo by Irvin Lin. Right photo courtesy of CA GROWN/BCMA.}

Back at home, I was inspired by both this trip and my previous trip to come up with this strawberry rhubarb slab pie with pistachio olive oil crumb topping. The peppery fruity olive oil really works well with the pistachio topping playing off of each other and highlighting the flavor of each. And the texture of the crumb topping is an ideal foil for the sweet tart strawberry rhubarb filling making this a great dessert for a picnic, friends gathering or just a Spring and early Summer dessert anytime.

A slice of strawberry rhubarb slab pie with pistachio crumb topping on a plate. with the remaining pie and a mug of tea next to it.

How to make this slab pie

Slab pies are similar to regular pies, but made in a rectangular baking sheet, which makes them easier to slice into smaller servings (perfect for large parties and gatherings) as well as a higher crust (and crumb) ratio to the filling.

Start with making a single pie crust by combining flour, sugar, and salt in bowl. Cut up cold butter into small cubes, then flatten and smash them with your fingers.

Left image is flour, sugar, salt in a bowl with cubed cold butter. Right image is a hand smashing the butter into flat pieces.

Drizzle ice cold water into the bowl, tossing until a shaggy dough forms.

Left image is cold water being poured into a bowl with pie crust ingredients. Right image is a fork tossing water into the dry ingredients for a pie crust.

Dump the mixture onto a clean surface, flatten with the palms of your hand, and then fold the dough over. Repeat this a couple of times to help create flaky layers, and then wrap in plastic wrap and chill in the fridge for at least an hour or overnight.

Left image is pie crust ingredients dumped onto a clean surface. Right image is the pie crust ingredients being folded over.

When the dough has firmed up, make the crumb topping by crushing or chopping the pistachios and adding them to a bowl with flour, rolled oats, which sugar, brown sugar, Turbinado sugar, cinnamon, ginger, and salt. Drizzle olive oil over the entire mixture, tossing until clumps form. Chill the bowl of crumbs while you make the filling.

Extra virgin olive oil being poured into a bowl with crushed pistachios, brown sugar, white sugar, flour and spices.

Make the filling by combing chopped rhubarb, strawberries, chopped kiwis, the zest of a Meyer lemon, the juice of a Meyer lemon, tapioca starch or cornstarch, olive oil, vanilla, cinnamon, black pepper, and salt in a large bowl. Set aside.

Left image is filling ingredients for a strawberry rhubarb pie. Right image is all the ingredients tossed together.

Roll out the dough into a large rectangle and fit it into a 9 x 13 x 1 in pan (also known as a quart sheet pan). Add the filling and bake for 30 minutes. Then sprinkle the pistachio crumbs over the filling and return to the oven to bake until the filling is bubbly, then cool to room temp and serve!

Baked strawberry rhubarb pie with pistachio crumb topping on a baking sheet.

Explaining the special ingredients

This recipe has a few uncommon ingredients that you typically won’t find in other recipes. Here’s why I’ve included them, as well as more common substitutions.

Turbinado Sugar: Sometimes called by its brand name “Sugar in the Raw” this coarse sugar is refined using a turbine, which is where its name comes from. I use it because the blonde sugar lends both a slightly molasses flavor as well as a sweet crunch. You can substitute regular coarse white sugar if you like, or substitute more brown sugar or white sugar instead (though you won’t get the nice crunch that the Turbinado or coarse white sugar will give).
Extra Virgin Olive Oil: I use extra virgin olive oil in the crumb topping and in the filling to give it richness and dimension. I always recommend using California EVOO when possible. Look for olive oil with the California Olive Oil Council seal, which means the olive oil has been tested and met the one of the highest standards in the world. The olive oil itself gives a lovely rich peppery and fruity note to the crumb topping, working especially well with the pistachios. But if you don’t want to use olive oil, you can substitute the same amount of melted butter in place.
Kiwis: Kiwis appear in the filling because of the high pectin content that they have. The sweet tart fruit plays well with strawberries (and rhubarb as well) and the high pectin means the filling naturally thickens with the need to use lots of starch, which can sometimes dull the bright fruit flavors. If you don’t have a kiwi, you can also grate an apple to add pectin and add a more neutral flavor. Or omit both of the kiwi/apple and increase the tapioca starch or cornstarch to 6 tablespoons.
Tapioca Starch: My preferred thickener for fruit filling is tapioca starch, which is fairly easy to find at well stocked grocery stores. It works better than cornstarch in acidic environments and won’t muddy the flavor of the fruit. But cornstarch is a good substitute as well and has been tested to work in this recipe.
Meyer Lemon: Meyer lemons are a hybrid between regular lemons and oranges. They have a tender fragrant zest and lower acidity than their regular lemon counterpart. If you don’t have a Meyer lemon you can easily substitute the juice and zest of a lemon or orange in its place. Or use 2 tablespoons of Balsamic vinegar for richer filling.

Three slices of strawberry rhubarb slab pie with pistachio crumb topping on ceramic plates.

How to Store this Pie

This pie is best eaten the day it’s baked (and cooled). But you can store leftovers at room temperature for 2 to 3 days. You can also freeze the pie (whole or in slices) for up to 3 months. Just freeze on a baking sheet until solid, then move to a resealable freezer Ziploc bag, placing parchment paper or wax paper between layers.

A slice of strawberry rhubarb pie with pistachio crumb topping on a plate with a scoop of vanilla ice cream on top of the pie. A mug of tea is behind the plate.

If you like this slab pie, here are a few other slab pie recipes that you might enjoy:

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