I doubled this recipe.
1 pound Roma tomatoes, cored and halved
1/2 medium white onion, cut into 1/2-inch slices
2 medium garlic cloves, peeled and smashed
1 medium serrano chile, stemmed
Put all vegetables in a roasting pan with olive oil, fresh cracked black pepper and other spices as desired. Cook indirect 550ish until tomatoes and onions are soft.
1 teaspoon kosher salt, plus more as needed
2 tablespoons coarsely chopped fresh cilantro
1 teaspoon freshly squeezed lime juice, plus more as needed
Add all ingredients in blender.