How to Make It
Remove the stems from 1 bunch of beet greens. Put the greens in a bowl, sprinkle with 2 tablespoons of the sugar and 1 tablespoon of the salt, and massage into the greens. Let sit for about 30 minutes, or until wilted.
Drain the greens and place in a clean large bowl. Add the carrot, scallions, garlic, and ¾ cup of the chipotle mezcal sauce and mix well. Transfer to a nonreactive container, cover, and refrigerate overnight.
Prepare a grill for high heat. (Prawns should be cooked quickly, so you need to have the embers going.)
Put the prawns in a large bowl. Drizzle with olive oil, sprinkle with salt and pepper and the chile powder, and mix well. Oil the grill grate and grill the prawns until the flesh is just opaque and nice grill marks have formed, about 1 minute per side. Remove from the heat and let cool.
While the prawns cool, put the cucumbers in a small bowl and sprinkle with the remaining 2 tablespoons sugar and 2 teaspoons salt. Let sit for about 10 minutes.
Remove the stems from the second bunch of beet greens and put the greens in a large bowl. Add wilted beet greens and mix well.
Divide the cucumber among six plates. Arrange the beet greens on top of the cucumber and scatter the radishes and mandarin oranges over them. Place the prawns on top and drizzle with the olive oil and the remaining ¼ cup of sauce. Serves 6.
Make Sauce: Combine all the ingredients in a blender and blend on high until smooth, adding more water if needed. Makes about 2 cups.