Strawberry and Rhubarb Crumble

INGREDIENTS

• 3/4 cup all purpose flour
• 6 tablespoons (3/4 stick) chilled unsalted butter, cut into 1/2-inch cubes
• 1/2 cup old-fashioned oats
• Large pinch of salt
• 12 ounces rhubarb (preferably bright red), ends trimmed, stalks cut crosswise into 1/2-inch-thick pieces Vanilla ice cream
• 1/2 cup husked hazelnuts, , coarsely chopped
• Vanilla ice cream
• 1/2 vanilla bean, split lengthwise
• 2/3 cup plus 1/2 cup sugar
• 1 pound strawberries, hulled, halved (about 4 cups)