Suet

Fat from around the kidneys of cows or sheep, suet is widely available in the United Kingdom. The leading UK brand of beef suet is Atora, which is sold in shredded form and is available online in the United States. Alternatively, you can ask your butcher to save suet for you. A vegetarian suet, also from Atora, is available, though it’s not quite as good. There are really no good alternatives, though cold shredded butter or solid vegetable shortening can usually stand in as a reliable substitute.