Rhubarb Crisp

Ingredients

• For the topping:
• 5 ounces light brown sugar
• 3 3/4 ounces whole wheat flour
• 4 ounces old-fashioned rolled oats
• 1 1/2 teaspoons ground cinnamon
• 1 teaspoon whole anise seed, optional
• 1 teaspoon Chinese five-spice powder
• 1/4 teaspoon Diamond Crystal kosher salt; for table salt, use half as much by volume or use the same weight
• 5 ounces unsalted butter, soft but cool, about 68°F
• 5 ounces raw pecan pieces
• For the filling:
• 2 3/4 pounds rhubarb, cut into 3/4-inch pieces, from around eighteen 24-inch stalks
• 10 1/2 ounces sugar
• 2 1/2 ounces tapioca flour, such as Bob's Red Mill
• 2 ounces elderflower liqueur or water
• 3/4 teaspoon Diamond Crystal kosher salt; for table salt, use half as much by volume or use the same weight
• 1/4 teaspoon baking soda
• To Serve:
• 1 recipe strawberry whipped cream or brown sugar whipped cream

Directions

1. For the topping, add the brown sugar, whole wheat flour, rolled oats, cinnamon, anise seed if you’re using it, five-spice powder, salt, and butter to the bowl of a stand mixer with the paddle attached. Beat on low until the mixture comes together as a heavy dough, about 5 minutes. You can also work it together by hand. Mix in the pecans, move the topping to a zip-top bag, and chill it until you need it, up to 1 month.
2. For the filling, set an oven rack in the lower-middle position and heat the oven to 400 degrees F (200 degrees C). Using the same stand mixer bowl, without washing it, stir together half the prepared rhubarb, about 5 1/2 cups; 22 ounces; 620g, with the sugar, tapioca flour, elderflower liqueur or water, and salt using a flexible spatula. It will look very dry, and that’s exactly right. Scrape everything into a 7- by 11-inch baking dish or a 9-inch deep-dish pie pan, scattering any extra sugar and starch over the surface, then cover the dish with foil. Set it on a foil- or parchment-lined half-sheet pan and bake until the rhubarb has softened and released its juices, about 30 minutes. While it bakes, put the rest of the fruit into that same bowl.
3. To finish, take the baking dish out of the oven and remove the foil. Scatter the baking soda over the hot rhubarb, then stir gently with a heat-resistant spatula until the juices start to foam. Spoon the hot mixture over the remaining rhubarb and fold it together, then transfer it back into the baking dish. Cover the fruit with handfuls of the prepared streusel, pressing each portion into a thin layer so the top is evenly covered. Bake again until the crisp bubbles all the way in the center, about 35 minutes more. The timing can change quite a bit depending on the shape and material of your baking dish.
4. Before serving, cool the crisp for at least 30 minutes, since the filling will be very hot and loose right out of the oven. It will continue to thicken as it cools to room temperature. If you like, serve it à la mode or with spoonfuls of strawberry or brown sugar whipped cream. Covered with foil, the crisp will keep 3 days at room temperature.