The sausages can be either hot or sweet, with fennel seeds or without. Just make sure they are fresh.
1/4 cup olive oil
2 garlic cloves, peeled and minced
2 onions, sliced
6 bell peppers, green, red or a mixture, cut into 1/2-inch - wide slices
salt to taste
8 hot or sweet Italian sausages, about 2 pounds
Heat the oil in a large skillet over medium heat. Cook the garlic until it begins to brown, and then discard it. You really just want to flavor the oil. Add the onions and cook until soft, stirring from time to time so they cook evenly. Don't let them brown. Add the bell peppers and salt, stir well and cover and cook over low heat until they're soft, about 30 minutes.
Meanwhile, cook the sausages. First pierce them all over with a fork and either broil them until they're golden, grill them, or cook them in another skillet over medium heat with several tbsp of water, turning them so they cook evenly. It will take about 15 minutes for the water to evaporate and the sausages to cook.
When the sausages are done and the peppers are ready, mix them together and cook in a skillet for about 5 minutes, for the flavors to blend. Serve with a crusty Italian bread.