In a saucepan, heat 2 tablespoons of the olive oil over medium heat.
Add the onions, and cook 4-5 minutes until they are soft and golden.
Add the bell peppers, garlic, bay leaf, crushed red pepper, dried parsley, salt, and black pepper.
Cook everything for about 3 minutes. Remove the bay leaf, and set aside.
Add the 2 cans of whole tomatoes including the juice. With a hand blender, crush the tomatoes. Be careful not to blend the tomatoes too much. You should leave a few chunks of tomatoes in the sauce.
Add the brown sugar and water. Cook for more 3 minutes.
Return the bay leaf to the pan.
Add the pesto, and cover the pan. Once it boils, lower the heat to maintain a low simmer.
Meanwhile in a skillet, heat the remaining 1 tablespoon of olive oil.
Add the Italian sausages, and sauté until they become brown on the outside but still raw inside.
Cut the Italian sausages into three pieces each, and add to the tomato sauce. Cook on low heat for about 1½ hours. You can also cook the sauce for longer (3-4 hours) if you have the time.
Before serving, remove the bay leaf. Serve it over spaghetti or zucchini noodles.
If you make this recipe, follow @primaverakitchen on Instagram, snap a photo and hashtag it #primaverakitchen. I'd love to see what you're making!