Preheat your oven to 375°F (190°C). Lightly grease an 8x8 inch baking dish or a similar-sized oven-safe dish.

In a large bowl, gently combine the sliced peaches, quartered strawberries, 1 tablespoon of flour, 0.75 cup of granulated sugar, lemon juice, and 0.25 teaspoon of cinnamon. Toss to coat evenly.

Pour the fruit mixture into the prepared baking dish and spread it out evenly.

In a separate medium bowl, whisk together the 1 cup of flour, rolled oats, 0.75 cup of brown sugar, 0.5 teaspoon of cinnamon, and salt for the topping.

Add the cold butter cubes to the dry ingredients for the topping. Use a pastry blender, fork, or your fingertips to cut the butter into the dry ingredients until the mixture resembles coarse crumbs with some larger pea-sized pieces.

Sprinkle the topping evenly over the fruit mixture in the baking dish.

Bake for 35-45 minutes, or until the topping is golden brown and the fruit filling is bubbly and tender. If the topping starts to brown too quickly, you can loosely tent the dish with aluminum foil.

Let the crisp cool for at least 10-15 minutes before serving. This allows the filling to thicken slightly. Serve warm, optionally with vanilla ice cream or whipped cream.