Creating your Mixed Berry Crisp is simple if you follow these steps:

1. Preheat the Oven: Start by preheating your oven to 350°F (175°C).
2. Prepare the Berries: In a large mixing bowl, gently toss together the mixed berries, granulated sugar, cornstarch, lemon juice, and vanilla extract until combined.
3. Transfer to Baking Dish: Pour the berry mixture into a 9×13-inch baking dish, spreading it out evenly.
4. Make the Crisp Topping: In another bowl, combine the rolled oats, flour, brown sugar, cinnamon, and salt. Stir to mix well.
5. Add the Butter: Pour melted butter over the dry mixture and mix until crumbly.
6. Top the Berries: Evenly distribute the crisp topping over the berry mixture in the baking dish.
7. Bake: Place the dish in the preheated oven and bake for 30-35 minutes, or until the topping is golden brown and the berries are bubbling.
8. Cool Slightly: Once baked, remove it from the oven and allow it to cool for about 10-15 minutes before serving.

These straightforward steps will help you assemble a delicious Mixed Berry Crisp that will be the highlight of any meal!