Gather ingredients: tomatoes (fresh or canned), olive oil, garlic, onion (optional), salt, black pepper, dried oregano or basil (optional), red pepper flakes (optional), sugar (optional), vinegar or lemon juice (optional)
Prep tomatoes: chop fresh tomatoes or crush canned tomatoes
Heat olive oil in a saucepan over medium heat
Sauté diced onion (optional) until softened, about 5 minutes
Add minced garlic and cook 30–60 seconds
Add tomatoes, salt, pepper, and herbs/spices
Simmer uncovered 20–45 minutes, stirring occasionally
Adjust flavor:
Add a pinch of sugar if too acidic
Add a splash of vinegar or lemon juice for brightness
Add more salt/pepper as needed
Blend for smooth sauce (optional): use an immersion blender or transfer to a blender
Cook to desired thickness: simmer longer for thicker sauce, add water/stock for thinner
Finish: taste and adjust seasonings
Serve immediately or cool and store in the refrigerator up to 4–5 days, or freeze for later use