For the Sauce: Coarsely chop the peppers and discard stems, taking care to use gloves when handling the very hot peppers.
Place the chilies, their seeds, the garlic, lemon juice and salt plus the desired amount of oil into a food processor. Puree the mixture and place into a glass jar and let flavors meld for several days.
The sauce should keep for up to 1 month in the refrigerator.
For the prawns/shrimp:
Toss the peeled and deveined prawns/shrimp into a bowl with the sea salt and set aside for 45 minutes.
Put the wooden skewers to soak in water. (So they will not burn on the grill).
When the prawns/shrimp are done marinating, toss them with the lime juice.
Put 3-4 prawns/shrimp on the skewer
Brush the prawns/shrimp with the peri-peri sauce, reserving some for dipping.
Grill the prawns/shrimp on a medium high heat for just a couple of minutes per side until they turn pink. Do not overcook.
Serve immediately with the reserved peri-peri sauce for dipping.