- Preheat oven to 400°F.
- Mix rhubarb, strawberries, ½ cup sugar, cornstarch and lemon juice in a large bowl.
- Toss well to coat.
- Divide mixture equally among six 1¼ cup custard cups.
- Mix butter, almond paste, and remaining ⅓ cup sugar in processor until well blended.
- Transfer butter mixture to medium bowl.
- Add flour.
- Using fingertips, work flour into butter mixture until moist clumps form.
- Sprinkle topping over rhubarb and strawberries, dividing equally.
- Place custard cups on baking sheet.
- Bake until filling bubbles and topping is golden (about 30 minutes).