Preheat grill to medium-high. Thread garlic cloves onto a wooden skewer. Place garlic skewer, chiles, and shallots onto grill. Cook, turning until softened and tender, about 10 minutes for the garlic and chiles, and 20 minutes for the shallots.
Remove veggies from the grill, and cool. Peel the garlic and shallots. Peel, seed, and remove the membranes inside the chiles (you may leave some seeds or membranes in if you want additional heat in the salsa).
Place the garlic, shallots, and chiles in the bowl of a food processor, and pulse to a coarse puree. Add the cilantro, soy sauce, and brown sugar, and pulse to combine.
Serve at room temperature, or refrigerate and serve cold.