For the topping:
2/3 cup flour
1/2 teaspoon baking powder
2 tablespoons sugar
2 tablespoons Demerara sugar (or turbinado sugar aka Sugar in the Raw)
1/2 t. lemon juice
1/2 stick of unsalted butter, melted
For the filling:
1 cup rhubarb, chopped into 1-inch pieces
1 cup strawberries plus a few extras, hulled, quartered
1 T. lemon juice
1/4 cup sugar (more if you think the rhubarb is too tart)
2 tablespoons flour
Pinch of salt
1. Pre-heat oven to 375°F. Prepare topping: In a mixing bowl, combine flour, baking powder, sugars and lemon. Add the melted butter. Mix until small and large clumps form. Refrigerate until needed.
2. Prepare filling: Toss rhubarb, strawberries, lemon juice, sugar, flour and the pinch of salt. Evenly distribute to the 4 little pots.
3. Remove topping from refrigerator and cover fruit mixture thickly and evenly with topping. Place little pots on a baking sheet, and bake until crumble topping is golden brown in places and fruit is bubbling beneath, about 40 minutes.