In a medium mixing bowl, put portobello caps, sliced onions, sliced bell pepper, and jalapeño.
In a small bowl or measuring cup, mix together oil, vinegar, grated garlic, salt, pepper, and thyme.
Pour the marinade over mushrooms, onions, and peppers.
Let set in the fridge for a couple of hours or overnight.
Heat an iron skillet Buy an Iron skillet here with a tbsp of olive oil or refined coconut oil.
Pull out the onions, and peppers and fry them on medium-low heat until caramelized.
While they are cooking, heat your grill and grill the mushrooms until done, flipping and adding leftover marinade as needed.
Build burger with portobello, onions and peppers, and blue cheese.