Add the potatoes to a medium pot and cover with water.
Heat the pot over medium-high heat and bring to a boil. Then, lower the heat and cook the potatoes until they are fork-tender, about 10 minutes.
Drain the potatoes and allow to cool slightly.
Add the potatoes, green onion, and peppers to a large bowl.
In a small bowl, add Vegenaise, vinegar, salt, pepper, and sugar. Combine. Stir Vegenaise mixture into bowl of potatoes, green onion, and peppers.
Chill the potato salad until ready to serve and garnish with chopped parsley, if desired.