On a recent trip abroad, I visited a theater complex. Among the snacks on offer were nachos, with hot cheese sauce, jalapeño peppers and salsa. It arrived and I stared in askance at the little, plastic pot of red stuff. "What's this?" "That's your salsa. Enjoy your day." That wasn't salsa. That was a few chopped tomatoes, shoved through a blender, with a spring of coriander. If that is your experience of salsa, then you are in for a serious treat in Mexico.
Admittedly, Mexican salsa does often use tomato (or green tomatillos) as its base. Coriander (or Chinese parsley) does have its place too. But there's more! Even the most basic salsa will have garlic, onions and a choice out of literally thousands of chiles, ranging from the mild to the blow your socks off strong. It never stops there. What gets added next can often be a jealously guarded secret; or it can be up to individual tastes. Chocolate in the mole; carrots; sesame seeds; paprika; nuts; any number of spices; sweetcorn; olives; peppers; fruits (mango is popular); lime juice; you name it and someone in Mexico will have experimented with it.
Making salsa is an art. Some of the fast food restaurants will use a blender for speed, but in the homes, and in the quality establishments, salsa is made in a molcajete.
The molcajete is used just like a pestle and mortar, though it is made out of basalt. It was used as a cooking utensil, in Mexico, way before the coming of the Spanish. The ancient Maya used one. Its very name comes from the Nahuatl language. The Atzec had something similar, though their's was made from ceramic. The point being that when a item has been used for over a thousand years, with no sign of being given up any time soon, you know that there's a reason. And that reason is the taste of the salsa coming out of it.
Each of the ingredients are added in separately and pounded into submission by the cook. The subtle flavors depend upon when they were added, and in which quantities, and how long they were allowed to influence the dish. You just don't get that in a blender.
Salsa, in Spanish, means 'sauce'. Most of these are served cold, though some recipes do call for cooked salsa. It can be eaten on its own, or as a dip with tortilla chips, or as a spread (think tacos).
The actual recipes can differ from restaurant to restaurant, and certainly from home to home. But there are regional variations too. The salsa served in Monterrey may be nothing like that presented in Guerraro.
For more information about salsas, plus some recipes, visit: Mexican Salsas by Luis Dumois.