1.In a large pot or pan with deep sides, preheat one tablespoon of the olive oil over medium high heat. Add in the zucchini and sauté until golden, about 5-8 minutes. Season with a pinch each of salt and pepper and transfer to a bowl.
2.Return the pot to the heat and add in the extra 2 tablespoons of oil. Heat to medium high, then add in the carrot, celery, and onion and sauté until translucent. Add in the garlic and sauté until fragrant, about 30 seconds.
3.Add in the tomatoes, bay leaves, oregano, basil, and chili flakes. Reduce heat to medium low and simmer for 30 minutes.
4.Meanwhile, transfer the mushrooms to a heat proof bowl and cover with 1 cup of boiled water. Allow to sit for at least 10 minutes. Remove the mushrooms, finely chop and add to the pot, along with 1/2 cup of the poaching liquid.
5.Near the end of the cooking process, add in the balsamic, sugar and season with salt and pepper.
6.Mix the cooked zucchini into the pasta sauce and heat until warmed through. Remove the bay leaves. Keep warm.