Heat large Dutch oven or skillet over medium heat. Add one tablespoon olive oil and cook Italian sausage for 12-15 minutes turning occasionally until browned on all sides . Transfer sausages to a plate and set aside.
In the same pot, add the remaining 2 tablespoons olive oil. Add the onions and peppers, oregano and cumin seeds, cover, and cook for 3–4 minutes, or until they begin to soften.
Add the mushrooms, tomatoes, and garlic. Toss to combine, cover, and cook for another 3–4 minutes, or until the mushrooms are tender and the tomatoes begin to break down.
Stir in the marinara sauce, salt and sugar. Reduce heat to medium low and simmer uncovered for 5 minutes.
Return the sausages to the pot and simmer for another 5-7 minutes, allowing the flavors to meld together.
Serve in individual bowls and garnish with fresh herbs.