For the marinade, whisk together balsamic vinegar, extra virgin olive oil, minced garlic, and tamari/soy sauce.
Remove stems of portobello mushrooms. You can also scoop out the gills of the mushrooms as well if you prefer, but this isn’t necessary.
Add the mushrooms to the marinade and toss to evenly coat. Let sit for 7 minutes and then turn. Let sit for another 7 minutes.
While the mushrooms are marinating, heat a grill or cast iron pan over medium heat.
When the mushrooms are ready, cook on the grill or cast iron skillet (add 1/4 tbsp of oil to the pan if using this method) for 3-4 minutes on each side until soft and golden brown. Baste with the remaining marinade a couple of times on each side while cooking.
Remove the mushrooms from the grill and finish with the Wild Foraged Fennel Pollen.