- 3/4 cup all purpose flour
- 2/3 cup plus 1/2 cup sugar
- 6 tablespoons (3/4 stick) chilled unsalted butter, cut into 1/2-inch cubes
- 1/2 cup old-fashioned oats
- 1/2 cup husked hazelnuts, toasted, coarsely chopped
- 1/2 vanilla bean, split lengthwise
- 1 pound strawberries, hulled, halved (about 4 cups)
- 12 ounces rhubarb (preferably bright red), ends trimmed, stalks cut crosswise into 1/2-inch-thick pieces
Combine flour, 2/3 cup sugar, and salt in medium bowl; whisk to blend. Add butter. Rub in with fingertips until mixture sticks together in clumps. Mix in oats and nuts. DO AHEAD Topping can be made 1 day ahead. Cover and chill.
Preheat oven to 375°F. Butter 11x7x2-inch glass baking dish. Place 1/2 cup sugar in large bowl. Scrape in seeds from vanilla bean; whisk to blend well. Add strawberries and rhubarb to sugar in bowl; toss to coat well. Scrape fruit filling into prepared baking dish. Sprinkle oat topping evenly over filling.
Bake crumble until filling bubbles thickly and topping is crisp, about 45 minutes. Let cool 15 minutes. Spoon warm crumble into bowls. Serve with ice cream.