Spray a medium nonstick skillet with cooking spray and place over medium heat. Add the scallions and cook until translucent, about 2 minutes. Increase heat to medium-high. Add the lemon juice and cook until almost all liquid evaporates, about 4 minutes. Transfer to a bowl to cool.

Place salmon in a food processor and pulse until coarsely ground. Add to scallions. Mix in the egg, dill, salt, and pepper. Form into 4 equal patties.

Spray a large nonstick skillet with cooking spray and place over medium-high heat. Cook patties until golden brown and cooked through, about 2 minutes per side. Serve on English muffins with desired toppings.