How to Make It
In a small dry skillet, toast the mustard seeds over moderate heat, shaking the pan, until lightly browned, about 2 minutes. Let cool.
In a medium bowl, combine the mustard seeds, lime juice, ginger, garlic, lime zest, salt and pepper. Stir in the peanut oil and then the cilantro and let stand at room temperature for 30 minutes. Scrape off most of the marinade before grilling.