Pork Wellington with Green Pea Duxelles and Champagne Sauce

Name: Pork Wellington with Green Pea Duxelles and Champagne Sauce
Prep time: 35 min
Cook time: 1 h 15 min
Total time: 1 h 15 min
Yield: 6 portions
Ingredients: 1 pork tenderloin; 1 ¼ tsp fine sea salt; 4 pinches ground black pepper; 80 g onions; 20 g unsalted butter; 200 g frozen green peas; 20 g fresh parsley leaves; 20 g water; 320 g puff pastry; 2 Tbsp breadcrumbs; 12 slices prosciutto; plain flour; 1 medium egg; 150 g whipping cream; 80 g onions; 10 g unsalted butter; 150 g Champagne; 150 g water; 10 g cornflour; 1 heaped tsp chicken stock paste, homemade