Position an oven rack about 4 inches below the broiler and heat the broiler on high. Arrange the tomatoes and garlic on a rimmed baking sheet and broil until the tomatoes are charred on one side, about 5 minutes. Turn the tomatoes and garlic and char on the second side, about 2 minutes longer. Let cool. Peel the tomatoes and garlic, discarding the skins and saving any juices that are released.

In a blender, briefly puree the tomatoes and their juices, the garlic, chipotle chile, and 1/2 teaspoon salt--it needn't be perfectly smooth.

In a medium, heavy-based saucepan, heat the oil over medium-high heat. When a drop of the pureed tomato mixture sizzles when added, pour in the remaining puree. Bring to a boil, stirring frequently. Adjust the heat to an active simmer and continue to cook, stirring frequently, until reduced to a scant cup and thickened to a sauce consistency, 8 to 12 minutes. Cool to room temperature. Stir in the cilantro and the lime juice. Season to taste with salt. Serve at room temperature.

This salsa can be kept in the fridge for up to one week.