Step 1: Saut Aromatics: Set the instant pot to the "Saut" function. Add olive oil, followed by chopped onion. Cook until softened, about 3-4 minutes. Add minced garlic, oregano, basil, and red pepper flakes (if using), and cook for another minute until fragrant.
Step 2: Add Ingredients: Turn off the "Saut" function. Add crushed tomatoes and vegetable broth to the instant pot. Season with salt and pepper to taste. Stir well to combine.
Step 3: Add Pasta: Add the gluten-free pasta to the instant pot. Gently press the pasta down into the liquid to ensure it is mostly submerged. Do not stir.
Step 4: Pressure Cook: Secure the lid of the instant pot and set the valve to the "Sealing" position. Select the "Manual" or "Pressure Cook" function and set the cooking time to half the time indicated on the pasta package instructions, minus one minute. For example, if the package says to cook for 10 minutes, set the instant pot for 4 minutes.
Step 5: Quick Release: Once the cooking time is complete, carefully perform a quick pressure release by moving the valve to the "Venting" position. Be cautious of the steam.
Step 6: Stir and Serve: Once the pressure has fully released, carefully open the lid. Stir the pasta well. If the sauce is too thin, set the instant pot back to "Saut" mode and cook for a few minutes, stirring occasionally, until the sauce thickens to the desired consistency.
Step 7: Garnish and Serve: Serve immediately, garnished with fresh basil leaves and grated Parmesan cheese (if desired).
Optional Tips: For a richer flavor, add a tablespoon of tomato paste along with the crushed tomatoes. To make this dish vegetarian, ensure the vegetable broth is certified vegetarian. Consider adding spinach or other leafy greens during the last minute of cooking for added nutrition.