Add 1-2 tablespoons olive oil to a medium sized skillet over low heat. Allow the olive oil to heat for a minute before adding minced garlic. Use a spatula to move the garlic as it cooks to prevent it from become burnt.
Once the garlic turns golden brown and aromatic, add the sliced onions. Stir the onions with the spatula and cook them until they become soft and brown on the edges.
Next, add the sliced mushrooms and corn kernels. Cook them for a few minutes before adding the diced tomatoes. Season the tomato sauce with rosemary, oregano, thyme, salt, and sugar. Adjust the flavor to your taste.
Pour the sauce over the spiralized zucchini noodles.