Leeks are related to garlic, chives, shallots, and onions. They have a sweet, oniony flavour that adds depth to soups, stews, pastas, and more! Generally they are used like onions and shallots, to build flavour at the start of a recipe. They are also delicious served as a side dish, grilled or roasted, gorgeous with a white sauce or just butter, sea salt and black pepper.