Cut the lemongrass stalks on an angle to create a 20x 6 inch spears.
Skewer one shrimp (through the thick part of shrimp and through the tail) on each lemongrass stick and place them on a baking tray.
In a medium sauce pan set over low heat combine the ginger, lime zest, lime juice, dark rum, brown sugar, chilli flakes, and butter. Season with salt and pepper.
Bring to a simmer while whisking constantly. Cook for approximately 5 minutes and remove from the heat.
Sprinkle the shrimp with salt, pepper, garlic and vegetable oil.
Preheat barbeque to high heat (425°F) (220°C)
Oil grill well to help prevent sticking.
Place the skewers directly on the grill and cook for approximately 1 minute.
Flip the skewers and baste the shrimp with the sauce.
Continue to cook 1 more minute.
Remove from grill and drizzle with remaining basting sauce so that both sides are well coated.
Serve and enjoy.