Preparation Combine the mayonnaise, yogurt, lemon zest and juice. Set aside. Toast the bread. To assemble the sandwiches, place the bread on a work surface and spread with the lemony sauce. Top with 1 leaf of lettuce (fold it if necessary), 1 slice of tomato, 1 slice of onion, one-fourth of the kipper filets and 1 ounce/28 grams of the avocado. Season with freshly ground black pepper. Tina's Tip:Kippers on toast is a classic meal in Great Britain and Ireland, while sardines are more popular in Scandinavia. Either fish works in this recipe, and if you have leftovers, toss them into eggs, a salad or a red sauce for a punch of flavor!Per Sandwich: Calories 380, protein 17 g, total fat 19 g, carbohydrates 37 g, sodium 690 mg, fiber 12 gNutritional analysis provided by The Truly Healthy Family Cookbook Reprinted with permission from The Truly Healthy Family Cookbook: Mega-nutritious Meals that are Inspired, Delicious and Fad-free by Tina Ruggiero, M.S., R.D., photography by Bill Bettencourt. Copyright © 2013 Tina Ruggiero. First published in 2013 by Page Street Publishing.