Chicken Stuffed Matzo Balls Recipe

Name: Chicken-Stuffed Matzo Balls Recipe
Ingredients: 1 medium onion, finely chopped (about 1 cup); 2 tablespoons chicken fat, unsalted butter, or vegetable oil (see note above); 1 3/4 teaspoon kosher salt, plus more to taste, divided; 1 pound ground chicken (preferably dark meat, see note above); 1/2 cup fresh dill, finely chopped; 3 eggs; 1/2 teaspoon freshly ground black pepper; 1/4 to 1/2 cup matzo meal, as needed; 7 cups matzo meal batter (see note above); 3 quarts chicken soup, for serving