Protein in a niçoise salad

TUNA

This fish is often packed in water or oil and comes in chunks or flakes, commonly found in sandwiches or sushi rolls.

A niçoise salad is a classic French dish that traditionally includes ingredients like green beans, olives, hard-boiled eggs, and tuna. The clue points to "protein" in this salad, which is the tuna—a fish commonly used in the recipe. Since "tuna" fits the letter count and matches the dish’s key protein, it’s the straightforward answer. No wordplay here, just a direct reference to a well-known culinary staple.