Sauté the Onions to Perfection: In a medium-sized pot, heat the oil over medium heat. Add the chopped onions and cook for about 4 to 5 minutes until they soften and turn translucent, releasing their savory aroma.
Blend in the Flavorful Ingredients: Stir in the remaining ingredients, except for the basil, creating a harmonious medley of flavors with the tomatoes, garlic, and seasonings.
Achieve the Ideal Consistency: Add enough water to achieve the desired sauce consistency, ensuring it's thin enough to coat the back of a spoon while still maintaining a luscious texture. As a rule of thumb, adding about 1/3 of the volume of the empty tomato can should do the trick.
Simmer to Delectable Delight: Cover the pot with a lid slightly ajar to allow steam to escape, and let the sauce gently simmer over low heat for 15 minutes. This process allows the flavors to meld and deepen into a tantalizing marinara.
Basil's Finishing Touch: Stir in the fresh basil, infusing the sauce with its delightful herbal notes. Continue cooking for an additional 5 minutes to fully integrate the basil's aroma and taste.
Fine-Tune the Flavor: Give your marinara a taste and make any necessary adjustments. Add salt and pepper to your liking, elevating the taste to perfection. For an extra touch of richness, drizzle a bit more olive oil if desired, adding a luxurious finish.