Coarse salt
1/4 cup honey
1/4 cup packed light-brown sugar
1/4 cup soy sauce
3 tablespoons rice vinegar
1 tablespoon Thai red curry paste
3 tablespoons vegetable oil
1 1/2 pounds top sirloin beef or shell steak, cut into 1 1/2-inch cubes
1 red onion, quartered, layers separated
1 can (20 ounces) sliced pineapple in juice, drained, slices quartered
1 package (10 ounces) thin dried Chinese noodles or spaghetti
1/2 cup chopped fresh cilantro
1/4 to 1/2 teaspoon red-pepper flakes, for serving (optional)