Sauté aromatics – In a large pot or skillet, heat olive oil over medium heat. Add onion and cook until soft and golden, about 5–6 minutes. Stir in garlic and cook 1 minute more.
Add tomatoes – Stir in crushed tomatoes, tomato paste, sugar, salt, pepper, oregano, basil, and red pepper flakes. Mix well.
Simmer – Add bay leaf, reduce heat to low, and simmer uncovered for 25–30 minutes, stirring occasionally, until sauce thickens and flavors deepen.
Adjust seasonings – Remove bay leaf. Taste and adjust seasoning with more salt, pepper, or herbs if needed.
Serve – Use immediately over pasta, on pizza, or as a dipping sauce. Garnish with fresh basil if desired.