With a mild flavour, it is perfect for roasting, or using as the base for stocks & sauces. Traditionally used in Mexican cooking. Heat treated variety. Why buy heat treated onion sets? It's frustrating when your beautifully forming onions decide it's time to develop seed & send up a flower stalk. Heat treating is a process that we carry out to prevent this happening. So whilst they are a little more expensive, you can be more confident of harvesting onions you can be proud of!