Onions tend to have a sharp or pungent flavor. It really depends on the onion and what exactly you are trying to convey to the listener. An onion might be strong, mild, aromatic, tear-inducing, acidic, salty, spicy, sweet, bitter, sour, or flavorful.
Recipes:
Grilled Cauliflower Steaks and Scallions
Shepherd’s Pie with Rutabaga Topping