Step 1
Preheat a charcoal or gas grill to a moderate heat level, ensuring the rack is positioned about 4 inches from the heat source. Alternatively, preheat your oven to 500°F (260°C).
Step 2
In a mixing bowl, combine the diced tomatoes, minced onion, chili, cilantro, lime juice, and a pinch of salt. Stir to incorporate and set aside, allowing the flavors to meld.
Step 3
Season the salmon fillet with salt and pepper. For grilling, lightly coat the fish with a small amount of oil. Place the salmon on the grill, skin side down, and cook for 4–5 minutes before turning it over. Continue cooking for an additional 3 minutes, or until the salmon reaches medium-rare doneness.
Step 4
If roasting, heat a nonstick skillet over high heat for about a minute. Add the neutral oil, followed by the salmon, skin side up. Sear the fillet for one minute, then transfer the skillet to the preheated oven. Roast for approximately 10 minutes, or until the fish reaches medium-rare. Let the salmon rest briefly before removing the skin. Flip the fillet and serve, accompanied by the prepared salsa fresca.