Heat small amount of olive oil in large, heavy pan, add the Italian sausage, and cook over medium-high heat until the sausage is browned on all sides.
Set sausage aside to cool on a cutting board.
Then add a bit more oil, add zucchini and yellow squash to the pan, and cook about 5 minutes, until it’s starting to brown slightly.
Remove squash from the pan and set aside.
Add a bit more olive oil, then add peppers, onions, and garlic and cook 3-4 minutes.
Add tomatoes to pan, gently combine the vegetables, lower heat to medium, and cook 5 minutes more.
Add zucchini and yellow squash back into pan with parsley, sugar, dried oregano, salt and pepper.
Reduce heat to low and cook uncovered about 30 minutes.
(You can add a little more olive oil if desired.)Cut the sausage into diagonal slices and add to the pan and cook about 30-45 minutes more.
When sausage is cooked through and stew is flavorful, add sliced or chopped fresh basil, season with sea salt and cook 5-10 minutes more.
Serve hot or room temperature, with more sliced basil and Parmesan cheese to add at the table if desired.
This Low-Carb Ratatouille Wanna-Be Italian Stew will keep in the fridge for several days and reheats well