Peel and devein the prawns.
For the marinade, peel and crush the garlic, mix with the lemon juice, soy sauce and pastis. Drizzle the prawns with this marinade. Reserve a little for deglazing.
Poach all the vegetables in boiling water and refresh them immediately. Melt the butter on the hotplate, add all of the vegetables, cook them 5 minutes and deglaze with the reserved prawn m