Warm 2 tablespoons extra-virgin olive oil in a large heavy-bottomed pot over medium heat until it shimmers, about 1 minute.

Add chopped yellow onion and minced garlic; cook, stirring occasionally, until onions are tender, translucent, and fragrant, about 5 minutes.

Stir in quartered bell peppers and sliced zucchini; cook, stirring occasionally, until veggies begin to soften and colors brighten, about 4 minutes.

Pour diced tomatoes with their juices into the pot; stir to combine and bring mixture to a gentle simmer.

Add dried oregano, bay leaf, salt, and pepper; reduce heat to low, cover partially, and simmer for 20 minutes until vegetables are tender but not mushy.

Remove the bay leaf, then stir in red wine vinegar to brighten flavors; taste and adjust salt and pepper to suit your preference.

Toss in fresh basil leaves off heat for a bright twist.

Serve hot in warmed bowls, garnished with chopped parsley or chickpeas for extra heartiness; pair with crusty bread or grains.