Preheat the oven to 425°F (220°C).

In a large bowl, combine sliced peaches, raspberries, and/or blueberries.

Add tapioca and brown sugar to the fruit mixture.

Toss until the fruit is evenly coated.

Pour the fruit mixture into a 3-quart baking dish.

Bake for 15 minutes to begin the cooking process.

While the fruit is baking, prepare the crisp topping in a separate bowl.

Combine flour, rolled oats, and salt.

Add cubed unsalted butter to the dry ingredients.

Use a pastry cutter or your fingers to cut the butter into the flour mixture until it resembles a coarse meal.

Once the fruit has baked for 15 minutes, remove it from the oven.

Scatter the flour mixture evenly over the top of the fruit.

Return the dish to the oven and bake for an additional 15-20 minutes, or until the topping is golden brown and the fruit is bubbling.

Let the crisp cool slightly before serving.

Serve warm with whipped cream or ice cream.