Cut the scallions and celery into a few large pieces. In a large pot, combine goat with scallions, celery, thyme, parsley, garlic, peppercorns and salt. Add enough water to cover. Bring to a boil. Reduce to a simmer and cook for 2 hours.
Add pumpkin and cook until just cooked, about 15 minutes. Remove pumpkin pieces with a slotted spoon or a spider.
Turn off heat and drain meat, reserving liquid. Separate meat from vegetables. Discard vegetables.
Transfer pumpkin to a blender with a little bit of the liquid and puree until very smooth.
Return the drained broth, meat and pumpkin puree to the pot. Add onion, vinegar, salt and pepper. Cook for about 20 minutes until the soup has thickened a bit.
Add carrots, potatoes and cabbage. Simmer for 20 minutes, until the vegetables are cooked through.
Add vermicelli and simmer another 5-10 minutes, until cooked.
Adjust salt and pepper, as necessary.
Serve with picklese.