Cook your fettuccine in a large saucepan of water, following the packet directions or until it's just al dente. Add the asparagus, snow peas and peas to the water, and cook for another minute. You want the veggies to be bright green and just tender. Drain the pasta and vegetables well.
Get started on the creamy lemon sauce. Heat a large frying pan over medium heat, then add some spring onions to the pan. Cook for one minute until the spring onions soften. Pour light thickened cream into the pan and bring it to a simmer.
Now add wholegrain mustard, horseradish cream and lemon juice. Give the sauce a stir occasionally and let it simmer for two to three minutes until it thickens slightly. Make sure you don't bring the sauce to a boil. When the sauce is ready, add the cooked fettuccine and vegetables along with some flaked smoked salmon and chopped dill. Gently toss to combine and then take it off the heat.
All that's left to do is season it with salt and pepper and sprinkle over some lemon zest. This delicious weeknight pasta dinner is on the table in under 30 minutes.