One of the most popular spices that add a delicious aroma with a slightly bitter taste is red pepper flakes. They are made by drying hot and sweet fresh peppers in the sun before they are crushed up. Varying from region to region, some chilli flakes are not roasted before being crushed. Used in all types of cooking, from soups to juicy hotpot dishes and casseroles to stir-fries. Also known to be a natural painkiller, red pepper flakes are believed to strengthen your immune system because it is enriched with vitamin C.