1. Make the cashew ranch: Place cashews in a bowl and cover with tap water. Soak for 1 hour. Drain cashews and add to a food processor along with 1 cup water, onion powder, garlic powder, and lemon juice; process until smooth, at least 1 minute. Combine cashew mixture with yogurt, herbs, salt, and pepper. Add more salt and pepper to taste as needed.
2. Make the cauliflower: Sift together rice flour, cornstarch, and salt. Add sparkling water, stirring until you have a pancake batter consistency. Heat oil in a wide, shallow pan over medium-high heat. Toss cauliflower florets in batter and working in batches, place battered cauliflower in oil. Make sure not to crowd the pan. Turn to fry evenly until all sides are golden brown. Remove florets from oil and drain on paper towels. Serve with cashew ranch.