You can adjust this recipe anyway you like. If you want to make a smaller batch I suggest cutting it down to 1 pound of tomatoes. But I find that everyone wants some it so I always make a bit more.
3 pounds Heirloom tomatoes
5 or 6 jalapeño or serrano chiles (amount depends on your heat preference)
1 white onion, coarsely chopped
3 cloves garlic
3 teaspoons sea salt
Toast the onions, chiles and garlic in a pan under the broiler in your oven until blackened. Cut the tomatoes in half and place them under the broiler until blackened as well. Add all of the ingredients to a blender and puree until smooth. Taste for salt and finish with chopped cilantro.