1. In a medium bowl, mix onion with 1 cup tomatoes. Season to taste with salt, pepper, and lime, if desired.
2. Place squash in a microwave-safe bowl with 2 Tbsp water. Cover and microwave for 6 minutes or until squash is tender enough to mash. Sprinkle with 1 tsp taco seasoning. Thoroughly mash and mix.
3. Heat a skillet coated with nonstick spray to medium. Cook soy crumbles, stirring, until thawed, about 3 minutes. Add remaining 1 cup tomatoes and 2 tsp taco seasoning. Cook and stir until hot, about 3 more minutes. If you like, microwave black beans for 30 seconds or until warm.
4. In a deep, flat-bottomed serving dish, evenly layer lettuce, squash, onion-tomato mixture, sour cream, beans, soy crumble mixture, cheese, and red peppers. Serve with veggies or baked chips.