Heat oven to 350°F. Place onions and milk in medium bowl; let stand. In deep fryer or 4-quart Dutch oven, heat oil (2 inches) to 375°F.
In resealable plastic food storage bag, mix Bisquick, salt and pepper until well mixed. Drain onions. Place onions in bag; shake to coat. Remove onions from bag shaking off excess. Gently place half of onions in oil; fry 2 to 4 minutes or until golden brown. Drain on paper towels. Repeat with remaining onions. Let onions stand while preparing bean mixture.
In ungreased 3-quart casserole, mix soup, soy sauce, pepper, cooked green beans and 1 1/2 cups of the onions. Bake 25 to 30 minutes or until hot and bubbly, adding remaining onions during last 5 minutes of baking.