Fresh Tomato Marinara with Spaghetti

From the garden

• 3 lb ripe tomatoes, roughly chopped
• 4 cloves garlic, thinly sliced
• 1 medium yellow onion, finely diced
• 1 cup fresh basil, leaves torn

From the pantry

• 3 tbsp olive oil
• 1 lb spaghetti
• ¼ tsp red pepper flakes (optional)
• Parmesan cheese (optional) — for serving
• salt — to taste
• ½ tsp granulated sugar (optional) — only if the sauce tastes sharp

1. Warm the olive oil in a wide pot over medium heat. Cook the onion with a pinch of salt until soft and translucent, about 5 minutes, then add the garlic and pepper flakes and cook 1 minute more, until fragrant but not browned.
2. Add the chopped tomatoes with all their juices and another good pinch of salt. Simmer uncovered, stirring now and then and crushing the tomatoes against the pot as they soften, 25–30 minutes, until the sauce is thick enough that a spoon dragged through leaves a trail.
3. Meanwhile, cook the spaghetti in well-salted boiling water until just shy of al dente. Scoop out a cup of pasta water before draining.
4. Taste the sauce — if it's sharp, stir in the sugar. Tear in most of the basil, then add the drained pasta and a splash of pasta water, tossing over low heat until the sauce clings, 1–2 minutes.
5. Serve topped with the remaining basil and Parmesan if you like.