If using dried beans, add the chickpeas to a medium bowl and cover with water by at least 1 inch (2.5cm). Let them sit, uncovered, at room temperature for 24 hours.
Preheat the oven to 375°F (190°C, or gas mark 5).
Add the drained chickpeas, onion, garlic, lemon juice, parsley, cilantro, cumin, coriander, cayenne, 1teaspoon (6 g) of salt, and ¼ teaspoon pepper to the bowl of a food processor. Pulse about 10 timesuntil the chickpeas are chopped. Scrape down the sides of the bowl, add the flour and baking powder, and pulse until the mixture is well combined.
Scoop out about 2 tablespoons of the mixture and roll it into a ball in the palms of your hands. Transfer to a lightly greased baking sheet and use a spatula to flatten into a ½-inch (1.3 cm)-thick disk. Repeat with the remainder of the mixture.
Bake the falafel until cooked through and tender, 25 to 30 minutes, flipping once halfway through.
Heat the oil in a large skillet over medium heat. Add the riced cauliflower, za’atar, salt, and pepper, and stir to combine. Cook, stirring occasionally, until the cauliflower is slightly softened, about 3 minutes.
To serve, divide the cauliflower rice and arugula among bowls. Top with falafel patties, bell pepper, avocado, sauerkraut, and a scoop of hummus.