Step 1

Heat broiler. Place tomatoes, onion, garlic, and jalapeños in a roasting pan or on a large rimmed baking sheet and broil until charred on top, about 4 minutes. Remove from broiler and turn vegetables over. Broil until other sides are charred, about 5 minutes. (Watch the garlic carefully and remove earlier if needed.)

Step 2

Transfer vegetables to a molcajete and mash into a coarse purée; season salsa with salt.