• Cut a small corner from the sausage packaging and drain off any excess liquid. Transfer to a plate; pat dry with a paper towel.

In a medium sauce pot over medium-high heat, warm 2 tablespoons oil until hot but not smoking. Add the sausage and cook, stirring to break up the meat, until lightly browned but not yet cooked through, 2 to 3 minutes. Using a slotted spoon, transfer the sausage to a plate. Do not clean the pot.
While the sausage cooks, start preparing the remaining ingredients.

• Peel and coarsely chop the red onion.
• Trim the ends from the celery; cut the celery on the diagonal into ½-inch lengths.
• Strip the thyme leaves from the stems.
• Trim the root ends from the black garlic cloves and remove the peel; using the side of a knife, smash the garlic.

In the same pot used for the sausage, warm 1 tablespoon oil over medium-high heat until hot but not smoking. Add the butternut squash, onion, celery, and thyme and season with salt and pepper. Cook, stirring occasionally, until the vegetables begin to soften and caramelize, 5 to 7 minutes.
Add the sausage and any accumulated juices, vegetable broth, and 2 cups water and season with salt and pepper. Bring to a boil, reduce to a simmer, and cook, stirring occasionally, until the vegetables are tender and the sausage is cooked through, 8 to 10 minutes. Add the kale and black garlic, season with salt and pepper, and cook, stirring occasionally, until the kale is just wilted, 2 to 3 minutes.
When the soup is almost done, chop the parsley.

• Strip the parsley leaves from the stems; coarsely chop the leaves.

Remove the pot from the heat and stir in the parsley and sherry vinegar. Season to taste with salt and pepper.

Transfer the soup to individual bowls and serve.