Preparation for red sauce pasta-
Roast onions or bell peppers in 1 tbsp oil for 3 mins on a high flame. Transfer to a plate to cool.
Roast tomatoes until mushy for about 3 mins. Cool this as well.
Blend them together to a puree. Set aside.
In a large pot, bring water to a boil. Cook pasta with salt until al dente (just cooked).
Drain off and rinse them. Drain in a colander. Set aside.

How to make red sauce pasta
Heat the same pan with more oil and fry garlic and chilli flakes until aromat.
Add onions and saute until golden.
Pour the puree and add salt.
Mix well and cook until it reaches a desired consistency. Make sure the sauce is not watery. Taste the sauce and adjust salt as needed. Add oregano.
Off the stove and add the pasta. Toss well until mixed.
Serve hot pasta in red sauce.