Walnuts

The walnut is a nut particularly rich in omega-3 fatty acids. This biochemistry makes it incredibly vulnerable to thermal and air oxidation (rancidity). Its pellicle contains pronounced tannins that give it an earthy bitterness. To avoid destroying its fragile fats, it is often incorporated at the very end of cooking or cold. In bread or an endive salad, it offers a fatty textural snap and a woody bitterness that contrast marvelously with the sweetness of blue cheeses.