In Dutch oven or flameproof casserole, heat oil over medium heat.
Stir in onions, paprika, salt, and pepper Reduce heat to low.
Cover and cook, stirring occasionally, until onions are very tender, about 15 minutes.
Increase heat to medium, stir in cabbage and cook, tossing, until wilted, about 5 minutes.
Add squash, potatoes, carrots, water, and wine, and bring to a boil over high heat Reduce heat to medium-low, cover and simmer, stirring occasionally, until vegetables are very tender, about 30 minutes.
Spoon goulash into bowls.
Top each with a dollop of sour cream and a sprinkling of onions.