In a large pot, heat the olive oil over medium heat. Add the diced onion, carrot, and celery, stirring occasionally, until they are softened and the onion is translucent, about 5-7 minutes.
Once your vegetables are tender, stir in the minced garlic, fennel seed, and crushed red pepper. Cook for an additional 1-2 minutes until the garlic is fragrant but not browned.
Carefully add the crushed tomatoes to the pot. Stir well to combine everything, and then add the bay leaf, freshly chopped basil, dried oregano, and season with salt and black pepper to taste.
Bring the sauce to a gentle simmer. Reduce the heat to low and let it simmer uncovered for about 30 minutes, stirring occasionally. This will allow the flavors to meld together beautifully.
After 30 minutes, taste the sauce and adjust seasoning if necessary. If you'd like a touch of sweetness, stir in the optional sugar to balance the acidity of the tomatoes. Remove the bay leaf before serving.