Ingredients
1 kg (2 lbs) very large shrimp (about 20-30)
1 clove garlic
5 ml (1 tsp) kosher salt
30 ml (2 tbsp) olive oil
10 ml (2 tsp) lemon juice
10 ml (2 tsp) chopped fresh oregano leaves 

Directions
Chop garlic with kosher salt to form chunky paste. Combine paste with oil, lemon juice and oregano, then toss with shrimp, making sure shrimp are well coated. Thread shrimp onto skewers. Preheat grill to high for about 15 minutes. Grill shrimp skewers on high 5-7 minutes, turning midway through, until shrimp are pink and lightly charred. Serve hot garnished with lemon wedges. Serves 4-6.

Note: If you leave the shells on, they’ll have more flavour, but if you don’t want messy fingers just peel the shrimp before cooking.
 

Source: The Cook’s Illustrated Guide to Grilling and Barbecue:
A Practical Guide for the Outdoor Cook