Preheat the oven to 170C/340F.
Place all of the pastry ingredients (except for the olive oil) into a food processor and pulse until combined. If the mixture is too sticky, add more ground almonds.
Grease your pie tin with the olive oil and place the pastry mixture inside it, pressing it along the bottom and up the sides until everywhere is covered.
Bake in the oven for 15 minutes.
Meanwhile, start making the filling. Place the lentils in a saucepan and cover with 500ml water, bring to the boil, then simmer for 15 minutes.
Break the tops from the asparagus spears. Add the asparagus, frozen peas and spinach to a large pan, cover with water, bring to a simmer and cook for 5 minutes. Drain, then set aside.
Cut the salmon fillets into chunks and remove the skin. Add the milk and salmon to a large pan, and bring to a gentle simmer. Cook for 4-5 minutes, then drain.
Heat the olive oil in a frying pan, slice the onion and gently fry until softened.
Whisk together the eggs, egg whites, Greek yoghurt, nutmeg and black pepper until combined, then add in the onion, peas, mustard, dill, lemon zest, salmon, spinach, and lentils.
When the pastry is ready - remove from the oven and pour in the filling mixture, then place your asparagus and fresh dill on top.
Place back into the oven and bake for a further 10-15 minutes, until the filling has set and the crust has started to brown.