That unique flavor you love in Mexican food (and can't figure out) is probably cumin.
Cumin is the pale green seed of Cuminum cyminum, a small herb in the Umbelliferae, or parsley family.
The seed is uniformly eliptical and deeply furrowed and frequently used in Mexican dishes, as well as Middle Eastern, Asian and Mediterranean cusine.
In addition to its unforgettable warm (and slightly bitter) flavor, it's also an antioxidant powerhouse.
Antioxidant Score (ORAC)=76,800
Store in a cool, dark, dry place.
Serving size: 1 tsp(s)cumin seed:8 kcal calories
Omega-6 / Omega-3 ratio: 16 : 1