Preheat the oven to 425°F (210C). Spread the cauliflower florets, purple potatoes, and sliced onions out over a baking sheet. Drizzle with olive oil and toss to coat. Season with salt and black pepper and roast in the oven for 20 minutes until the vegetables are tender and golden brown on the edges.
Meanwhile, cover the lentils with 3 cups (about 700 ml) water in a saucepan and bring to a boil. Lower the heat and cook gently until soft, about 20 minutes. Drain the excess cooking liquid and set aside.
In a blender, combine the apple cider vinegar, olive oil, maple syrup, Dijon mustard, cumin, cloves, cinnamon, 4 whole prunes, salt, and pepper and blend until smooth and creamy. Thin with a ¼ cup (60ml) water to loosen consistency if dressing is too thick. Transfer vinaigrette to a bowl and set aside.
Divide ingredients into four serving bowls. To each bowl add a serving of the lentils, roasted cauliflower, potatoes, and onions and arrange some chopped kale, beet slices, and California prunes around the bowl. Drizzle the vinaigrette over each bowl. Garnish with cilantro and enjoy!