Tomato or jitomato (Lycopersicon esculentum) needs no introduction, except to say that the quality of Mexican tomatoes is very good and some of what you find in U.S. markets won’t do. Unless truly ripe, flavorful fresh tomatoes are available, you may be better off using a good brand of canned Italian tomatoes for cooked sauces.
My recipes often specify “roasted tomatoes.” To roast a tomato, so as to deepen the flavor before adding it to a dish, place it on a heated griddle or cast-iron skillet over high heat and turn so the skin blisters and blackens all over. Or blacken them under a broiler, turning as necessary. Peel off the blackened skin before using. This should be done over a bowl to catch the juice—and don’t be religious about removing all the blackened bits. I love the slight smokiness they contribute.