In a large bowl, combine ground beef, soy sauce, sesame oil, chopped garlic, ginger, and scallions. Mix until combined. Optionally, cover and let marinate in the fridge for a couple hours. No worries if you skip this step, but if you have the time I recommend it since it'll make the filling more flavorful.
When ready to assemble the dumplings, prepare your workspace by having your filling and dumpling wrappers nearby, along with a parchment or Silpat lined baking sheet and a small bowl of water.
Working one at a time, place a generous tablespoon of filling onto a single dumpling wrapper. Dip your fingers in water, and outline the edges of the wrapper with the water. Fold in half, and then form into your desired shape. Here's a useful guide for various ways to fold dumplings: Ten ways to fold dumplings| Red House Spice Finish filling and shaping the rest of the dumplings until you're all out of filling. At this point you can either cook or freeze the dumplings. The below cooking times will be longer if using frozen dumplings.
Pan fry method: To pan fry the dumplings, you'll need a large skillet with a lid. Heat 2-3 tablespoons oil, enough to coat the bottom of the pan, in the skillet over medium heat. Once the oil is hot, place as many potstickers in the oil, seam side up, so that they are not touching. Cook undisturbed until the bottom starts to turn golden brown, about 2 minutes. Pour 3 tablespoons water in the pan, cover with a lid, and shake a bit to disperse the water. Cook with the lid on for 3 minutes, then removing with a spatula or tongs and place on a paper towel lined plate. Repeat with rest of the dumplings.
Steam method: Lightly coat the steamer with a bit of oil to prevent sticking. Steam dumplings in a steamer with the lid on for 6 minutes, or until dumpling skin is cooked through.
Serve immediately with your favorite dipping sauce. My favorite is spicy chili oil!