Cumin seed, is commonly used in Mexican cooking (comino) as well as a common ingredient in Indian and Malaysian cooking. Overused cumin becomes very overpowering so keep that in mind when adding this spice to your recipe.
Cumin is used in many, if not most chili recipes. For best results, toast whole cumin seed in a hot, dry skillet just until it becomes aromatic. Remove, let it cool, then grind it in a electric spice grinder or in a mortar and pestle.
If you don't have cumin and you need a substitute, here are a couple of alternatives (per teaspoon needed):
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