Spicy and Creamy Slaw

Name: Spicy and Creamy Slaw
Ingredients: ½ small red onion or 1 medium shallot, thinly sliced; 3 Tbsp. apple cider vinegar or white wine vinegar; ½–1 serrano chile or jalapeño, thinly sliced into rounds; Kosher salt, freshly ground pepper; 1 small garlic clove, finely grated; ½ cup plain whole-milk Greek yogurt or mayonnaise; 2 Tbsp. extra-virgin olive oil; 1 tsp. finely grated lemon zest; 1 Tbsp. fresh lemon juice; 1 medium head of savoy or green cabbage (about 2 lb.); ½ cup chopped dill or parsley