Boil spaghetti with salt until al dente. Prep other ingredients while it cooks. Drain the pasta but save 1/2 - 1/3 cup of the water.
In large sauté pan, heat oil over low - medium heat. Add minced garlic, onions; cook and stir until tender.
Stir in mushrooms for few minutes until wilted. Season with pepper, italian herbs and chilli flakes. Add in about 1/3 pasta water to thicken the sauce and bind the pasta.
Combine diced red and green tomatoes into the sauce and stir for few minutes. Add in medium chopped green tomatoes and stir for 2-3 minutes. Toss in pasta and canned tuna and heat through. Taste with salt.