Finely dice tomatoes, onions and serrano chiles; add chopped cilantro and garlic, and season with salt and lime juice.
Avocado & Cotija Pico: Add about 1 lb diced avocado and 4 oz crumbled Cotija cheese. Adjust salt and lime juice; add more minced serrano chiles, if desired.
Three-Chile Pico: Roast and peel 3-4 Poblano chiles and 3-4 Fresno chiles; dice and add to base pico de gallo; adjust seasonings.
Melon Pico: Add about 12 oz each of diced watermelon and diced cantaloupe. Add Tajin seasoning to taste.
Grilled Pineapple Pico: Add 24 oz grilled diced fresh pineapple; adjust seasonings.