1. Peel the asparagus, and blanch them in boiling water for 4 minutes. Cut off the tips and slice the asparagus into thin rounds.
2. Heat the oil in a large, heavy saucepan over medium heat. Add the salmon and cook briefly, until it is almost cooked through. Remove it with a slotted spoon and set it aside. Add the shallots and cook until they are translucent.
3. Add the rice and cook for 1 minute. Add the wine and cook, stirring, until the liquid is absorbed. Add 1/2 cup of broth at a time, stirring constantly. Each time the broth is absorbed, add the next portion.
4. When the risotto is almost ready, stir in the asparagus. Cook until it is al dente.
5. Stir in the butter. Return the salmon to the risotto. Mix gently, adding the lemon juice, salt, and pepper; serve immediately.