How to Make It
Preheat the oven to 350°. In a large bowl, toss the strawberries and rhubarb with the sugar, cornstarch, vanilla and salt. Let stand at room temperature for 30 minutes, tossing occasionally.
Spread the almonds in a 9-inch pie plate and toast, stirring once, until golden and fragrant, about 7 minutes. Let cool completely.
In a food processor, pulse the almonds with the flour, baking soda and salt until the almonds are coarsely ground. In the bowl of a stand mixer fitted with the paddle, cream the butter with both sugars until fluffy, about 3 minutes. Scrape down the side of the bowl. Add the egg yolk and vanilla and beat at medium-high speed for 2 minutes. Scrape down the bowl again. Add the almond-flour mixture all at once and mix at low speed just until incorporated.
Pour the fruit into the pie plate. Dollop teaspoon-size clumps of the batter over the fruit. Bake until the topping is deeply browned and the juices bubbling up around it appear thickened, about 45 minutes. Let cool slightly; serve warm.