The purpose of chili paste is to add spice to a dish, so you can use more or less than what the recipe calls for depending on your spice tolerance. I prefer any of the Huy Fong chili pastes (they always have a green cap and a rooster on the front) but there are many, many different brands to choose from. For the best selection of chili pastes, visit an Asian market or the international foods section of your grocery.