Place red potatoes into a large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until tender, about 25 minutes. Drain and chill in freezer until cold, about 30 minutes.
Slice potatoes and place into a large salad bowl; toss potatoes with green onion. Whisk olive oil, red wine vinegar, lemon juice, garlic powder, onion powder, salt, black pepper, oregano, sugar, rosemary, and red pepper in a bowl. Pour the dressing over the potatoes and toss. Serve immediately or chill until serving time.