In large skillet, brown beef until fully cooked; drain.
Add water; bring to a boil. Slowly stir in pasta and seasoning mix. Return to a boil.
Reduce heat to medium. Boil uncovered, 9-11 minutes or until pasta is just tender and most of the water is absorbed, stirring frequently.
Stir in green onions or tomatoes, if desired.
Sauce will be thin. Let stand 3-5 minutes to thicken.