Peel shrimps and langoustines. Place the peeled seafood in the fridge and save for later.
Heat a big pot on medium heat with some olive oil.
Add the yellow onion and fry for 2-3 minutes, until it starts to turn translucent. Add the garlic, leek and carrot and stir together and fry for 1-2 minutes more.
Next add the tomato paste, stir everything together and let it fry for another 2-3 minutes.
Add the water, white wine, bay leaf and thyme to the pot and bring to a boil. Lower the heat and let it cook for about 20-30 minutes, until reduced. Place a fine meshed stainer over a bowl and pour the seafood stock through the strainger. (This part can be prepared in advance)
Bring water and salt to a boil in a pot. Add the asparagus and let it simmer for 2-3 minutes. The asparagus should just turn slightly soft but still be crunchy on the inside. Drain the asparagus and place in a bowl of ice cold water. (This step can be prepared in advance)
When ready to cook preheat a big pan over medium heat with some olive oil.
Remove the seafood from the fridge and let it come into room temperature.
Drain the asparagus and cut into smaller pieces. Save the tops for serving.
Add the shallot and fry for 2-3 minutes, just until it starts to turn golden brown. Add the garlic, stir together and fry for another 1-2 minutes.
Next add the avorio rice, stir together with the onions and let it fry for 3-4 minutes, until it starts to turn golden brown.
Add the dry white wine to the pan and let it deglaze it. Stir together with the rice. Let it simmer until almost evaporated.
Add about 2 dl (1 cup) seafood stock along with the lemon juice, stir together and let the risotto simmer on low heat. Stir regularly/constantly. Add a little bit more seafood stock at a time (1/2-3/4 dl at a time), as needed. Cook for about 15 minutes.
Add the grated parmesan cheese, stir together.
Cook for 20-25 minutes in total. Add the shrimps, langoustines and cut asparagus to the risotto and stir together, turn off the heat.The risotto should be creamy but the rice should still be al dente.
Meanwhile the risotto cooks preheat a pan over medium/high heat with some olive oil.
Fry the remaining langoustines in the hot pan for 1-2 minutes, until golden brown.
Divide the risotto between plates. Top with fried langoustines, asparagus tops and grate lemon zest over the dish. Serve immediately.