1. To make the sauce: In a medium pot, sauté garlic in oil until just golden, being careful not to burn. Add brown sugar, soy sauce, sriracha, lime juice, and lime zest. Allow to simmer until thickened, about three to five minutes.
2. Add soba noodles, scallions, sesame seeds, and jalapeño or chili pepper and mix. Just before serving, add peanuts and cilantro.