Pre-heat the oven to 425 F.
Bring water to a boil. Thinly slice the red onion and add to a glass container large enough to submerge the onion in water. Add the vinegar and a pinch of salt. Pour the boiled water over until all of the onion is submerged. Set aside.
Cut the potatoes in half lengthwise and score the flesh with a criss-cross pattern using a knife. Drizzle the halves with 1 tsp of the oil and rub to coat each. Sprinkle with a little of the paprika, garlic powder and salt and pepper. Place cut-side down on the baking sheet and roast for 30-40 minutes until easily pierced with a fork.
Remove the leaves and stem from the cauliflower, cut it into florets and place on another baking sheet. Drain and rinse the chickpeas and blot with a paper towel or dish cloth to dry. Add to the pan with the chickpeas. Add the remaining 1 tsp oil and sprinkle with paprika, garlic powder, salt and pepper. Use your hands to mix and coat. Roast for 25-30 minutes until browned and tender.
Peel and grate the beets.
Add a few drops of oil to the chopped kale and massage with your hands for 30-60 seconds until softened and dark green in colour.
Add all of the dressing ingredients to a mini food processor or blender with a pinch of salt and pepper. Blend until smooth and creamy. Check the consistency and slowly add more water 1 tbsp at a time until you reach your desired thinness, this may be 2-4 tbsp additional water depending on the tahini used.
Assemble the bowls by dividing the kale, beet and roasted cauliflower and chickpeas between 4 servings. Add two potato halves to each bowl. Top each with pickled onion, 1 tbsp pumpkin seeds, 1/4 of the avocado and a drizzle of the tahini sauce.