Peel and devein the prawns, leaving the tails on.

Place the prawns in the lemon and lager marinade for 2 hours at room temperature.

Cut off the last 2 inches of each asparagus spear. Peel the bottom two-thirds of each stalk.

Bring a large pot of water to a boil for the asparagus.

Combine the thyme, mashed potato flakes, salt and pepper.

Dip the prawns in the beaten egg whites, then into the potato mixture.

Blanch the asparagus for 5 minutes. Drain and keep warm but not hot.

In a saute pan over medium-high heat, cook the prawns for 2 minutes on each side.

Serve the sauteed prawns on a bed of the asparagus.