For the salmon with crispy crust, sprinkle the salmon fillets with lemon juice and season with salt and pepper on both sides.
Coarsely grate the pumpkin, apples and potatoes with a food processor. Halve onion, cut into strips and sauté in hot olive oil until translucent.
Add pumpkin, apples and potatoes, salt and fry for about 10 minutes. Finely grate ginger and add to pumpkin vegetables.
Preheat oven to 200 degrees top and bottom heat. Roll up puff pastry, cut into 4 rectangles and place on a baking paper.
Roll up the edges of each rectangle so that the edge is slightly raised and brush with beaten egg.
Prick the center a few times with a fork and pre-bake in the oven for 10 minutes. Brush with olive oil, place salmon fillet on top and cover with pumpkin vegetables.
The edge of the puff pastry should remain free. Mix breadcrumbs with salt and parmesan. Cut cold butter into small pieces and add.
Rub all ingredients together until crumbles are formed. Spread crumbles on top of pumpkin vegetables, press everything down well and bake for another 20 minutes until crumbles are golden brown.
Arrange the salmon with crispy crust on the puff pastry bed and serve.