In a large bowl, combine shiitake mushrooms and corn starch. Mix well and toss into a frying pan. Cook until the mushrooms start to brown and become caramelized (this may take 5-10 minutes, be patient and flip the mushrooms as they brown on each side). Move the mushrooms back into the mixing bowl and set aside.
In the same frying pan, heat the remaining olive oil. Toss in garlic, ginger, and chili pepper. Sauté until fragrant.
In a small bowl combine brown sugar, corn starch coconut aminos, sambal chili sauce, and rice vinegar. Mix well and add to the garlic and ginger mix in your frying pan. Stir the sauce until it becomes thick and begins to simmer. Toss in mushrooms and mix to coat.
Serve over rice with optional garnish of green onions, avocado, cabbage and spicy mayo. Enjoy!