Place the chiles, garlic and tomatoes in a saucepan, cover with water and set over medium-high heat. Simmer for 10 minutes, until the tomatoes are cooked and mushy, and the chiles are rehydrated. Place the cooked chiles, garlic and tomatoes into the jar of a blender, along with ½ cup of their cooking liquid, the cilantro, and salt, and puree until completely smooth.