Roast 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 to 5 mins. Add half of the chili flakes and cool this as well.
Blend them together to a smooth puree. Set aside.
In a large pot, bring water to a boil. Cook pasta with salt till al dente (just cooked). Follow the cook time on the pack.
Drain to a colander and reserve ½ cup of the drained stock. Rinse the pasta and keep aside.
Heat the same pan with more oil. Fry garlic and the other half of chili flakes (optional) until aromatic. This should just take you a minute.
Add onions and saute until golden. Pour the pureed tomatoes and add salt.
Mix well and cook until it reaches a thick sauce like consistency. Make sure the sauce is not runny. Taste the sauce and adjust salt as needed. If the sauce is too tangy, simply add some sugar & more chilli flakes to balance the flavors and taste.
Add the herbs and turn off the stove. Stir the pasta into the red sauce. If it is too thick, you may add a splash of the reserved stock.
Serve red sauce pasta hot with a side of grilled veggies or meat and salad. Even a cheese sandwich or a cheese toast goes well.