Preheat the broiler; line a baking sheet with foil. Mix the ground beef, 1/4 cup water, 2 tablespoons hoisin sauce, 1 minced garlic clove, 1 teaspoon ginger, 3/4 teaspoon salt and a few grinds of pepper. Form into 12 meatballs. Arrange on the prepared baking sheet and broil, turning once, until browned and cooked through, 6 to 7 minutes.
Meanwhile, bring a large pot of water to a boil. Add the noodles and cook as the label directs; drain and rinse under cold water. Toss with 1 teaspoon vegetable oil to prevent sticking. Whisk 1/3 cup water, the oyster sauce, sesame oil, remaining 1 tablespoon hoisin sauce, 1/4 teaspoon salt and a few grinds of pepper in a liquid measuring cup.
Heat the remaining 2 tablespoons vegetable oil in a large nonstick skillet over medium-high heat. Add the remaining 2 minced garlic cloves and 2 teaspoons ginger, the scallions (reserve some of the greens for topping), cherry tomatoes and snow peas. Stir-fry until the snow peas are bright green, 30 seconds to 1 minute. Add the noodles and toss. Pour in the sauce mixture and toss until mostly absorbed, 1 to 2 minutes. Divide the noodle mixture and meatballs among bowls. Top with the reserved scallion greens.