To make the mustard dipping sauce, stir together the mustard, lemon juice, 1/2 teaspoon coriander, 1/2 teaspoon cumin and 1/4 teaspoon pepper in a small bowl. Set aside.
Combine the remaining 1 1/2 teaspoons coriander, 1 1/2 teaspoons cumin and 1/4 teaspoon pepper in a large bowl. Add the shrimp, tossing to coat.
Preheat the barbecue. Thread the shrimp onto four long skewers. Place the shrimp on the barbecue and cook until opaque throughout, about 1 minute per side. Serve barbecued shrimp at room temperature or chilled, with the mustard sauce for dipping.
Per serving: 111 calories, 23 g protein, 2 g total fat, 0.3 g saturated fat, 180 mg cholesterol, 1 g total carbohydrate, 0.5 g sugars, 0.3 g fibre, 563 mg sodium