Mix together the ground turkey, egg, onion, garlic salt, and pepper. Form meatballs using a tablespoon measure.
Heat the oil in a skillet over medium heat. Brown meatballs in oil. Transfer meatballs to a paper towel to drain.
In small saucepan saute onion in butter. Add soup, milk, and peas. Heat on medium-low until peas are soft. Add sour cream. Stir. When hot, serve. Add sour cream to thickness desired.