Melt the butter in a saucepan over medium-low heat.
Stir the flour into the butter and let it cook, bubbling lightly, for about a minute. Whisk in the milk gradually and add the second half of the lemon pepper.
Cook the sauce for about 12 minutes, stirring frequently until it has thickened.
Remove from heat and whisk in the cream cheese until it melts.
Add the lemon juice and zest, green onions and crab meat. Return to the element and stir occasionally at very low heat, keeping it warm.
Barbecue the salmon on an oiled grill and cook covered for about 10 minutes. If the pieces have skin, place them skin down. The fish should flake whin pressed with a fork.