1. Preheat your oven to 375°F (190°C). Lightly grease a 9-inch tart pan with a removable bottom.
2. In a medium-sized bowl, mix the cooked brown rice, mozzarella cheese, Parmesan cheese, and egg until well combined. This mixture should hold together when pressed.
3. Press the rice mixture into the prepared tart pan, making sure to evenly cover the bottom and sides. Use the back of a spoon to smooth the surface.
4. Bake the crust for about 10 minutes, or until it’s lightly golden. This step helps the crust to set and become slightly crispy.
5. Meanwhile, drizzle the sliced tomatoes with olive oil and sprinkle with dried basil, oregano, salt, and pepper.
6. Remove the crust from the oven, and arrange the seasoned tomato slices in a circular pattern on top of the crust.
7. Return the tart to the oven and bake for an additional 20-25 minutes, or until the tomatoes are tender and slightly caramelized.
8. Let the tart cool for a few minutes before garnishing with fresh basil leaves. Slice and serve warm.

As you make this tart, remember that cooking is an art, not a science. Feel free to adjust the seasonings to suit your taste. A sprinkle of red pepper flakes can add a nice kick if you’re in the mood for something spicy.