These spices are the ones that provide enhancement and flavor to Mexican dishes. Most of these flavor spices can be found anywhere in the world, though certain regions may have different variations of the plant it came from, which accounts for a difference in the taste. Garlic and onions can be found anywhere but their strength and flavor are different all around the world. Taiwanese garlic for instance, may be big and bulbous, but they have significantly less potent flavor than the native garlic of Northern Philippines, which are much smaller but incredibly flavorful. Red or purple onions have very strong flavors while white onions have a more moderated and subtle flavor. It all depends on the variety, and sometimes, location.
These are some of the spices Mexican food usually come with:
Epazote is an uncommon spice better known with the name “Mexican Tea” though users should be careful with it, as it is poisonous in large quantities.
Cumin: Cumin comes in the form of seeds, and are used mainly for their very distinctive arom and flavor. It's potency comes from its essential oil content.
Oregano: Oregano is usually paired with tomatoes, which thus makes it an essential item in most Mexican cuisines, which is largely heavy on tomatoes. Like cumin, it has a distinct aroma and flavor, although it has a tendency to become bitter when used in large quantities.