Preheat the oven to 450 degrees F.
Add the tomatoes and red onion to a bowl and drizzle with oil. Season with salt and pepper. Add to a greased baking sheet. Add the garlic to a square of tinfoil, drizzle with olive oil and seal. Place on the sheet tray and roast for 25 minutes, until charred and tender.
Remove from oven and let cool for a few minutes. Add the vegetables and garlic to a food processor along with jalapeno, cilantro and lime juice; pulse until chunky. Taste for seasoning and season with salt and pepper, if necessary.
Add 1 tablespoon olive oil to a large nonstick skillet over medium-high heat. Once hot, add the fish and cook for 4 minutes per side. Top with the roasted salsa.