Preheat the oven to 425°F.

To prepare the salad, trim the beets by removing any beet tops and the tips of their roots. Dot each beet with a touch of clarified butter, then wrap each in parchment paper and again in aluminum foil. Roast the beets for 45 to 60 minutes, until they yield under the pressure of a fork. Refrigerate the beets for at least 8 and up to 24 hours.

To prepare the vinaigrette, whisk the kombucha tea with the salt, allspice, cloves, and the walnut and olive oils. The vinaigrette will store at room temperature for up to 3 weeks, but remember to shake it vigorously before dressing the salad because the oil will separate from the tea and spices when left sitting.

Just before serving, heat a skillet over medium-high heat for 2 to 3 minutes until very hot. Toss in the walnuts and toast them for 3 to 5 minutes, stirring frequently to avoid scorching. Remove the cold beets from the fridge, peel them, and chop into bite-sized pieces. In a large bowl, toss the beets with the sliced onion and toasted walnuts. Drizzle with the vinaigrette, toss again, and serve.