You may well find the Mediterranean spicy sausage dish addictive. It is important to set aside the browned vegetables separately, as they are cooked in layers later. Try to turn them over in step 3 in one piece; if this seems unlikely, leave them alone. They will still taste fantastic.
Sausage Alternatives: American andouille; Chorizo Mexicano; Salsiccia di Calabria; Chistorra
Note: French mergues — a characteristic kick makes this North African-style sausage perfect for grilling and serving with bland starches.
To make the ratatouille, heat 4 tablespoons of the oil in a large, heavy frying pan over medium heat. Separately cook the peppers, then zucchini, then the onion and tomatoes together, and lastly the eggplant, until browned. Set each aside separately.
Remove the pan from the heat. Place in the pan a layer of eggplant, then a layer of zucchini, then the bell peppers, then scatter over the garlic and parsley, and season well. Top with the tomato and onion mixture, and press everything down with a heatproof plate.
Return the pan to a low heat and cook for 30 minutes, until the vegetables are soft. Remove the plate using an oven mitt. Turn the vegetables gently with a spatula, and cook for 10 minutes over high heat until any liquid has evaporated. Set aside.
Pierce the merguez and broil, fry, or grill until well cooked and browned all over. Serve with the ratatouille, warm or at room temperature, and some crusty bread.