Heat the sesame oil over medium heat in a large skillet. Add onion, garlic and ginger and cook until golden brown, about 5 minutes.
Add the mushrooms and chopped spinach and cook for another 5-7 minutes, until the spinach becomes soft. Stir in the black beans, diced tofu, soy sauce, maple syrup, turmeric, sriracha and 5-spice if using. Cook for 5-7 minutes, stirring regularly. Taste and adjust seasonings if needed, adding more soy sauce for saltiness, sriracha for spiciness and/or 5-spice for more flavor.
Remove from heat, transfer to a large bowl and let cool 15 minutes.
Divide the dumplings dough into 2 balls. Roll out each ball into a round as thin as you can (about 1 mm thick). I rolled out the dough between two sheets of parchment paper to make sure it doesn't stick, you can also dust with cornstarch. IMPORTANT: the dough needs to be rolled out very thin, I insist on this because otherwise, the dumplings will take longer to cook and might be doughy.
Lightly press the edges of the round with your fingers to make it thinner than the center.
Place a tablespoon of filling in the center of a wrapper. Wet your finger and run some water (not too much) around the edges of the wrapper. Fold the wrapper to form a purse-like shape, alternatively, you can shape it into a half moon if you prefer. Make sure to press with your fingers to seal the dumpling. Set aside and cover with a damp kitchen towel while you prepare the rest
Heat two tablespoons of oil in a large skillet over medium-high heat. Fry the dumplings 20-30 seconds, or until the bottom is golden brown. Lower the heat to medium heat and add ½ cup water. Cover immediately with a lid and let "steam" until the dumplings are tender and no water remains, about 10 minutes.
Remove from heat and serve immediately with the sesame dipping sauce.