Tarragon Garlic Buttered Portobello Mushrooms in Foil (1 PKT) Grilled portobello mushrooms make a delicious vegetarian main or side dish! Wrapped in a foil together with our Tarragon compound butter with olive oil and a hit of lemon to produce a delicious coating for our grilled portobello mushrooms to elevate the mushrooms even more! Defintely a delightfully tasty treat for mushroom lovers.