Put the salmon fillets in the first tier and steam for 3 mins until the salmon has changed colour. Throw the asparagus spears in with the salmon and continue to steam for 4-5 mins until the asparagus is tender and the fish is cooked.
While everythings steaming, make a dressing by whisking together the olive oil, lemon juice and mustard. Tip the cannellini beans and spinach into a large bowl. When the asparagus is cooked scoop it into the bowl, then stir in the dressing. Divide the vegetables between two plates and sit the salmon on top.
