Soak the dried shiitake mushroom in a bowl with 1/4 cup of water for about 10 minutes. When the mushrooms are soft, squeeze out excess liquid back into the bowl. Do NOT throw away! You should have about 1 1/2 tbsp of mushroom water left. Set aside. Remove shiitake mushroom stems, roughly chop and set aside.
In a pan over medium high heat, add bacon and cook for 2 minutes, until cooked but not crunchy. Add thyme and olive oil and cook for a minute. Turn the heat up to high and add button mushrooms. Cook for about 3-4 minutes, until mushrooms are golden brown. Add shiitake mushrooms and shishito peppers and cook for 3-4 minutes, until mushrooms are caramelized and shishito peppers slightly charred. Turn off the heat and add garlic salt. Stir well and season to taste with salt and pepper. Serve immediately.