Remove the outside leaves from the cabbage. Cut the cabbage lengthwise into quarters remove the core. Cut cabbage into very thin strips. Peel onion, chop finely and fry in butter until tender. Add the cabbage and red wine. Cover and simmer for about 10 minutes. Purée the mixture in a blender in two batches. Mix with crème fraiche. Season with salt and pepper.
Soak the gelatin in cold water. Rinse and peel carrots and cut into small pieces. Rinse zucchini and cut into pieces. Cook carrots in boiling salted water for about 4 minutes, then add zucchini and cook for another 4 minutes.
Add a little of the carrot water to the gelatin to dissolve and mix with the vegetable purée. Mix in carrots and zucchini to the purée Pour mixture into a chilled 1 liter (about 1 quart) loaf pan. Refrigerate for about 4 hours or until set.