Mix potatoes and carrots in 3-quart saucepan; add enough water to cover. Heat to boiling; reduce heat to medium. Cover and cook 8 to 10 minutes or until tender; drain in colander. Wipe out saucepan with paper towel.
Melt margarine in same saucepan over medium heat. Cook onions in margarine 2 minutes, stirring occasionally. Stir in flour. Gradually add milk, stirring constantly, until mixture thickens and boils.
Stir in potatoes and carrots, peas, salt and pepper. Cook 5 to 6 minutes, stirring occasionally, until peas are tender.
Stir in dill weed. Cook 2 minutes, stirring constantly. Top each serving with chopped egg and, if desired, additional dill weed.