masa harina
A fine corn flour made from corn treated with lime, or nixtamalized, and dried; the base for corn tortillas, tamales, and other masa doughs. Nixtamalization is what gives it its distinct flavor and lets it form a pliable dough -- it isn't simply ground dried corn.
Buying guidance
Do not confuse it with cornmeal or ordinary corn flour on the shelf -- both are ground corn, but neither has been nixtamalized, so they won't form a workable tortilla or tamale dough no matter how much water is added. Buy a bag with a recent date from a store with good turnover; it can taste stale or lose its characteristic flavor if it sits too long.
Substitutions
- Fresh prepared masa, sold refrigerated at some markets -- ready to use, often with better texture than reconstituting masa harina.
- A different brand of masa harina -- fine cup-for-cup; brands vary slightly in grind and flavor but are functionally interchangeable.
- Omit -- there's no real substitute for making corn tortillas or tamale dough; cornmeal will not form the same dough.
Tips & common mistakes
Once hydrated into dough, it dries out and cracks within minutes if left uncovered, so keep it under a damp cloth or plastic while working rather than letting it sit exposed. Add water gradually rather than all at once -- too much makes the dough sticky and hard to shape, and it's easier to add more than to take it back out.
Storage
Store the dry flour airtight in the pantry away from heat; being a whole-grain corn product, it can lose its characteristic lime aroma and turn stale faster than white wheat flour, so refrigerating or freezing it extends freshness if it won't be used up within a few months.