Looking for a new veggie burger alternative? Give this savory-yet-sweet option a try. One bite and you’ll want to put this recipe for Vegan Portobello and Pineapple Teriyaki Burgers on repeat this grilling season. Our method uses leftover pineapple juice from a can of pineapple to make a simple teriyaki sauce. This flavor-packed mushroom burger will brighten up any cookout and have all your friends clamoring for the recipe.