Pickle the onions by mixing equal parts salt and white wine vinegar to cover thinly sliced red onion in a bowl. Add water until submerged, refrigerate for at least 1 hour, preferably overnight.

Cook the pasta in a large pot of salted boiling water for 10-12 minutes until slightly over al dente. Drain and rinse under cold water.

Combine cooled pasta, cottage cheese, sliced scallions, and drained canned salmon in a large mixing bowl. Add pickled onions with some pickling liquid.

Squeeze lemon juice over the pasta mixture. Drizzle in pickling liquid and add everything bagel seasoning. Gently combine and adjust seasoning to taste.

Serve immediately or refrigerate for up to three days. Refresh flavors with additional pickling liquid if storing.