Microwave vinegar and ⅛ teaspoon salt in medium bowl until steaming, 1 to 2 minutes. Add radishes and jalapeño and let sit, stirring occasionally, for 45 minutes. Drain vegetable mixture and return to now-empty bowl; set aside for serving. Combine mayonnaise, water, and garlic in second bowl. Season with salt and pepper to taste; set aside for serving.
Process pork rinds in food processor to fine crumbs, about 20 seconds; transfer to shallow dish. Place almond flour in second shallow dish. Beat egg, remaining ¼ teaspoon salt, and pepper in third shallow dish.
Pat cod dry with paper towels. Working with 1 piece of cod at a time, dredge in flour; dip in egg mixture, letting excess drip off; then coat with pork rind crumbs, pressing gently to adhere, and transfer to plate.
Heat oil in 12-inch nonstick skillet over medium heat until shimmering. Cook cod until deep golden brown and crisp on all sides, about 5 minutes. Transfer cod to paper towel–lined plate and let drain briefly. Place one piece of cod in each lettuce leaf and top with pickled vegetables, mayonnaise sauce, and cilantro. Serve.