Salmon Burgers With Quick Pickled Cucumbers

Name: Salmon Burgers With Quick Pickled Cucumbers
Ingredients: 1/4 cup rice vinegar; 1 tablespoon sugar; kosher salt and black pepper; 1 Kirby cucumber, very thinly sliced; 1/4 sweet or white onion, thinly sliced; 1 1/4 pounds skinless salmon fillet, cut into 1-inch pieces; 4 scallions, thinly sliced; 4 hamburger buns