In a small bowl, whisk together chili powder, cumin, paprika, coriander, cayenne pepper, and salt to taste (I like 2 teaspoons). Whisk in cornstarch if desired.
Cornstarch: This is a thickening agent found in store-bought packets. It's totally optional.
To make tacos: Add 2 tablespoons of seasoning for every pound of ground meat. 2 tablespoons seasoning is equivalent to one packet of store-bought.
Yield: This recipe makes 1/2 cup taco seasoning (without salt or cornstarch). Assuming 2 tablespoons of seasoning per pound of meat, the full recipe as written is enough taco seasoning for 4 pounds of ground meat.
Storage: Store covered in a cool, dark place and use within 6 months.