Prepare cauliflower according to directions. Place in a bowl; mash with a potato masher. Stir in onion, flour, garlic, 1/2 teaspoon salt, pepper, rind, potatoes, cheese, and eggs. Form into 8 patties. Heat a large nonstick skillet over medium-high heat. Add oil; swirl. Cook patties 4 minutes on each side. Combine 1/8 teaspoon salt, yogurt, and remaining ingredients; serve sauce with fritters.