How to Make It
In a small skillet, combine the mustard seeds, peppercorns, chile powder, bay leaf, celery seeds, coriander seeds and ginger and stir over moderate heat until fragrant, about 2 minutes. Transfer to a spice grinder and let cool completely, then grind to a powder. Stir in the salt.
Light a grill or preheat a grill pan. Thread the shrimp onto 4 metal skewers. Alternate the scallops and salmon cubes on 4 more metal skewers. Brush the skewers with the olive oil and season generously with the spice mix. (Reserve any remaining spice mix for another use.)
Grill the skewers over moderately high heat until the seafood is lightly charred and just cooked through, about 4 minutes. Sprinkle the seafood with the parsley and serve with lemon wedges.