Cut the mushrooms in half, lengthwise. Use a sharp paring knife to cut a shallow diagonal criss cross pattern on the cut side of the mushroom.
Heat a large skillet over medium high heat until hot. Swirl in 1 tablespoon of avocado oil.
Place half of the mushrooms cut side down in the pan, making sure not to overcrowd the pan. Cook for 2 to 4 minutes or until nicely browned and then flip over and cook for an additional 2 to 3 minutes until browned on both sides. Transfer the mushrooms onto a platter.
Swirl in another tablespoon of avocado oil into the empty pan and cook the remaining mushrooms the same way.
When the mushrooms are finished cooking, decrease the heat to medium and add the last tablespoon of avocado oil. Add the shallots, garlic, ginger, and Thai chili pepper into the empty pan. Stir-fry for 1 minute or until the shallots are softened.
Stir the cooked mushrooms back to the pan, along with any reserved liquid.
Pour in the fish sauce and lime juice and toss well to combine. Taste for seasoning and adjust with additional fish sauce or lime juice if needed.
Transfer the mushrooms to a serving platter. Scatter on the fresh herbs and enjoy!