A rich and flavorful tomato sauce packed with hearty vegetables, perfect for a comforting meal.
Heat the olive oil in a large skillet over medium heat.
Ensure the oil is hot but not smoking to avoid burning the vegetables.
Add the chopped onion, carrot, garlic, celery, and bell pepper to the skillet and sauté until softened.
Stir frequently to prevent sticking and ensure even cooking.
Transfer the sautéed vegetables to the slow cooker.
Use a spatula to scrape all the flavorful bits into the slow cooker.
Add the zucchini, mushrooms, crushed tomatoes, sugar, salt, and black pepper to the slow cooker.
Mix gently to combine all ingredients evenly.
Cook on high for 5-6 hours, stirring occasionally.
If the sauce thickens too much, add a splash of water or broth.
Stir in the fresh basil and parsley just before serving.
Adding fresh herbs at the end preserves their vibrant flavor.
Serve the sauce over your favorite pasta or as a base for other dishes.
Garnish with grated Parmesan cheese for an extra touch.