Preheat a cast-iron skillet over high heat until it starts to smoke. Roast the tomatoes and jalapeño in the dry skillet until charred, turning occasionally until most sides are blackened. Place into a bowl and cover with plastic wrap to steam and loosen the skins.
Using a mortar and pestle, grind the peeled garlic and the salt until it forms a paste.
Once the jalapeño is cool enough to handle, peel the skin off and remove the stem. Peel the tomatoes. The skins can be left in for added color and flavor, but some find them hard to digest. Roughly mash the jalapeño with the garlic. Add the tomatoes and pound again, keeping the salsa somewhat chunky. Taste the salsa for seasoning and serve.
- 6 medium tomatoes (or tomatillos)
- 1 jalapeño
- 1 to 2 cloves fresh garlic
- 3/4 tsp kosher salt