In a small bowl, whisk together the garlic, cold water, and lemon juice. Transfer to a glass jar or plastic container and refrigerate for 1 to 2 days.

In a medium skillet, heat the vegetable oil over medium-high heat until shimmering. Add the onions and cook for 5 to 7 minutes, until soft and translucent. Stir in the chili oil and remove from heat to cool.

In a medium bowl, combine the beef, cooked onions, scallions, soy sauce, oyster sauce, ginger, black pepper, and salt. Mix until well blended.

Place a large mixing bowl over a damp paper towel. Add the flour and make a well. Gradually add the just-boiled water while mixing with a wooden spoon until lumpy. Knead the dough until it comes together, adding water if necessary, then knead on a lightly floured surface until smooth and elastic.

Place the dough in a zip-top bag, seal tightly, and let rest at room temperature for 15 minutes to 2 hours.

Divide the dough into quarters. Roll each piece into a 1-inch-thick log and cut into 8 pieces. Flatten each piece to about ¼ inch thick.

Roll each disk with a rolling pin to about 3 to 4 inches in diameter. Fill each wrapper with 2 tablespoons of filling, patting it down lightly. Fold the dumpling into a half-moon and pinch to seal.

Heat a skillet over medium-high heat and add 1 tablespoon of oil. Arrange dumplings in a circle, frying for 1 to 2 minutes until golden brown.

Carefully add about ⅓ cup water to the skillet, cover, lower the heat to medium, and cook for 8 to 10 minutes until the water evaporates. Fry for an additional 1 to 2 minutes until bottoms are crisp.

Transfer dumplings to a serving plate. Serve immediately with the Raw Garlic Sauce.