Cucumber Salad

Name: Cucumber Salad
Prep time: 30 min
Total time: 30 min
Cuisine: American
Ingredients: 1 small red onion, halved lengthwise, thinly sliced; 2 lb. Persian or English cucumbers, cut into 1/4"-thick rounds; 2 1/4 tsp. (or more) kosher salt, divided; 2 tbsp. extra-virgin olive oil; 1 tbsp. apple cider vinegar; 1 tbsp. fresh lemon juice; 1 tbsp. whole-grain mustard; 1 tsp. honey; 1/4 tsp. black pepper; 1/4 tsp. crushed red pepper flakes (optional); 1/3 c. chopped fresh dill; 1/4 c. thinly sliced chives