In a stainless steel saucepan combine the water, shallots, pepper, salt and vinegar. Bring to the boil and simmer very gently for 20 minutes, adding a little extra water if it dries up.
Pass through a fine nylon strainer into a small saucepan, forcing the onion through. There should be about 1/3 cup. Add the cream and mustard and place on a very low heat.
Cut the butter into cubes and one by one whisk them into the sauce until you have a smooth, creamy sauce. Press plastic wrap onto the surface of the sauce to prevent skinning or separating, and set aside, keeping warm.
Bring a large pot of salted water to the boil. Add the pasta and cook to al dente, about 7 minutes. Drain, toss with a few teaspoons of olive oil and set aside.
Cook the salmon in a lightly oiled nonstick pan over high heat, for about 1 1/2 minutes on each side, until seared on the surface and still pink inside. Remove and let rest while you prepare the avocado.
Cut avocados into small cubes and toss gently in a bowl with lemon juice, black olives and chopped herbs.
Gently stir the butter sauce through the drained pasta, and carefully fold in the avocado mixture and the salmon cut into bite-sized cubes. Serve into warmed bowls and garnish with sprigs of fresh herbs.
Taste was sensational, texture nice, however their was way too much butter in the butter sauce and this made it very oily 600/700g butter is a huge amount should it be 60/70 g which would have been enough. Capers could have been used instead of olives at half qty and a squeeze of lime before eating bought ou the flavours. - 11 Aug 2010
I did the same thing and followed the recipe with 600g of butter. A pool of butter in the end. The 2nd time was much better - used 60g. Must be a typo. Doing it again tonight, can't wait! - 29 Aug 2013