Dipping sauce: Mix together dipping sauce ingredients in a bowl and store in the fridge until ready to serve.
Prep shiitake: Soak shiitake mushrooms in a bowl of water for a couple hours until hydrated. Or if you're short on time, soak them in hot water for 20-30 minutes until soft. Squeeze out excess liquid from the hydrated shiitake - save this liquid plus the soaking liquid for cooking the gyoza. Finely chop shiitake.Tip: Shiitake can be quite dirty, so strain the soaking liquid through a fine sieve before using it to cook the gyoza.
For frozen tofu: Make sure your tofu is completely thawed. To do this, you can take the tofu out of the freezer a night or two before and thaw in the fridge. Or, if you don't have that much time, boil in water for 10 minutes or so until thawed all the way through.
Press tofu: Remove excess water from tofu using a tofu press or nut milk bag. Or crumble the tofu and squeeze water out by hand.
Parcook Veggies: Add cabbage (and shiitake mushrooms if using fresh) to a microwave-safe bowl with a tablespoon of water, cover, and microwave 1-2 minutes, until cabbage is slightly tender but still crisp (mushrooms should be slightly soft and start to release some liquid).
Remove Excess Liquid: Let the veggies sit until cool enough to handle, then use your hands, cheesecloth, or a nut milk bag to squeeze out excess liquid.
Mix: Crumble tofu into a big mixing bowl and add in the cooked veggies, chives, garlic, ginger, miso, soy sauce, sesame oil, and pepper. Mix until well combined.
Make Gyoza: Lay out the gyoza skins on a clean surface and place a dollop of filling in the center, making sure there is still room to fold up the skins.
Lightly dip your index finger in water and wet the edges of the gyoza skins. This will help the skin stick together when you fold them up. Fold and crimp your gyoza skins so that no filling is falling out. Repeat until you use up all the filling.
Cook Gyoza: Heat a pan over medium heat and add a thin layer of oil (about 1 tbsp). Add gyoza to the pan, flat side-down, making sure they don’t touch each other. Fry the bottom of the gyoza for 1-2 minutes until crispy and browned on the bottom, then add about 1/4 cup water (or strained shiitake liquid) to the pan and cover with a lid. Reduce heat to medium low and steam for 3-5 minutes or until water evaporates and gyoza skins are transparent. Remove from pan and repeat the process with remaining gyoza.
Serve immediately with dipping sauce. Gyoza is best enjoyed hot. Leftovers can be stored in the fridge for up to 3 days or frozen up to 2 months.
Notes
Dried Shiitake: If using dried shiitake, save the liquid you rehydrated them in for steaming the gyoza in the last step.Tofu: Frozen tofu will produce a chewier texture while fresh tofu will be more soft. If using fresh tofu, be sure to press it to get most of the water out. I like to put my tofu in a nut milk bag* and squeeze out the water.Chives: If you can't find chives, you can also use 3-4 green onions.Gyoza Skins: Some gyoza skins contain egg, so make sure you check the packaging if you want this dish to be completely vegan. If you can't find egg-free gyoza skins, try wonton skins as these usually do not contain egg.Dipping Sauce: This is the basic gyoza dipping sauce. If you want something with extra flavors, try adding in a little bit of sugar and/or chili oil. I also like to serve my gyoza with this green onion sauce.