Make a big batch of Roasted Salmon and Vegetables and use the leftovers for this speedy supper later in the week.
In a large bowl, flake and mash salmon fillets. Stir in roasted vegetables, water chestnuts, egg white, ginger, and soy sauce until combined. Add flour and stir to combine. Divide into 4 patties. Lightly coat a large nonstick skillet with nonstick cooking spray and heat over medium; add patties and cook until golden brown and cooked through, about 8 minutes, flipping halfway through. Serve burgers on buns with lettuce and Chinese mustard, if desired.
A smear of hot Chinese mustard adds a nice kick to this sandwich. Look for it in your international aisle.