Mince one clove of the garlic and place it in a small bowl. Add the olive oil, soy sauce and 1/2 teaspoon of the salt. Whisk to combine.
Place the portobello mushroom caps in a resealable bag or a large container. Pour the soy sauce mixture over top. Use a pastry brush to ensure the mushrooms are evenly coated. Place the mushrooms in the fridge and let marinate for at least 3 hours.
Cut the corn off the cob and place it in a large bowl. Mince the remaining garlic clove and add it to the bowl. Add the jalapeno, lime juice, yogurt, cheese, cilantro, chili powder, cumin, coriander seed and the remaining salt. Stir to combine. Cover the stuffing and transfer to the fridge until ready to cook.
When ready to cook, spoon the corn stuffing into the marinated portobello caps and set aside.
Heat one side of a charcoal or gas BBQ until smoking. Place the portobellos on the unlit side and cover. Let cook for 15-20 minutes.
Remove the portobellos and top with avocado slices, pickled red onions, fresh cilantro and crumbled cheese. Serve immediately with beer.