Heat a deep nonstick skillet over medium-high heat. Add the onion and cook, stirring regularly, until it begins to brown.
Add the bell pepper, jalapeño, and garlic. Cook for approximately 2 minutes, stirring frequently so the garlic doesn’t burn.
Stir in the cooked brown rice, tomatoes, black beans, cumin, ancho chile powder, chipotle chile powder, and smoked paprika. Cook over medium-high heat for approximately 15 minutes, stirring frequently. Add a small amount of reserved tomato juice or vegetable broth if the mixture becomes dry. Season with salt and black pepper as needed.
Warm each tortilla in a separate dry nonstick skillet over medium heat for approximately 40 seconds, turning once. Keep the warmed tortillas covered with a damp clean kitchen towel.
Place approximately 1 cup of filling just below the center of each tortilla. Fold the bottom edge over the filling, fold both sides inward, and roll closed. Arrange seam-side down and serve warm with optional hot pepper sauce.