Vegetarian Stuffed Peppers

Name: Vegetarian Stuffed Peppers
Ingredients: 3/4 cup uncooked long-grain brown rice; 6 large red, orange , or yellow bell peppers; 1 tablespoon extra virgin olive oil; 1 large yellow onion , finely chopped; 2 large cloves garlic , minced; 1 1/2 teaspoons ground cumin; 1 1/4 teaspoons smoked paprika; 1 teaspoon kosher salt , plus more to taste; 1/2 teaspoon black pepper; 2 medium carrots , diced; 1 stalk celery , diced; 8 ounces button mushrooms , sliced then roughly chopped; 1 cup low sodium vegetable stock or water; 8 ounces firm tofu , drained and cut into 1/2-inch cubes; 2 packed cups baby spinach; 1 tablespoon lemon juice; 5 ounces Gruyere cheese , grated