My Grandmother's Simmering Fresh Roma Tomatoes

Ingredients

• 2 lbs fresh Roma tomatoes, diced
• 1 tablespoon olive oil
• 1 medium onion, finely chopped
• 3 cloves garlic, minced
• 1 teaspoon dried oregano
• 1 teaspoon salt, adjust to taste
• ½ teaspoon black pepper
• ¼ teaspoon red pepper flakes, optional
• 1 tablespoon fresh basil, chopped, for serving
• 1 teaspoon balsamic vinegar, optional