This is a thick, hash-brown-like dish, good any time of year. Simply replace the matzo meal with 2 tablespoons of all-purpose flour. Do not make this in advance and reheat it; that negates its crispiness. 
To add some color, grate 2 medium carrots and stir into mixture or 1 medium carrot and 1 small zucchini. Don’t be alarmed if the potatoes discolor slightly after grating. -- Betty Gordon 

Note: For Rosh Hashana and other holidays, dietary restrictions for Passover need not be observed as noted below. Regular margarine may be used. 

Hands on time: 30 minutes  Total time: 1 hour and 30 minutes  Serves: 10

Ingredients:

1 large onion, peeled 
6 medium baking potatoes, peeled (about 4 pounds) 
2 large eggs 
1 teaspoon salt or to taste 
6 tablespoons (3/4 stick) kosher for Passover margarine, melted 
2 tablespoons matzo meal 
2 tablespoons kosher for Passover margarine 

Instructions:

Place rack in upper third of oven and preheat to 400 degrees. 
In a food processor with the shredding disc or with a hand grater, grate the onion and transfer to a large colander. Grate potatoes and add to onion (you will need to do this in several batches). Drain well, squeezing out excess moisture. 
In a very large bowl, whisk eggs, salt, melted margarine and matzo meal. Stir in potatoes until well-combined. 
Place 2 tablespoons margarine in a 9-by-13-inch baking dish. Melt in oven and tilt dish to coat evenly. Transfer potatoes to baking pan, distributing evenly. Bake uncovered for 15 minutes. Reduce oven temperature to 375. Bake for 45 more minutes, or until top is crisp. Cut into squares. -- Adapted from “Fast & Festive Meals for the Jewish Holidays: Complete Menus, Rituals, 
and Party-Planning Ideas for Every Holiday of the Year” by Marlene Sorosky (William Morrow, $27, 1997)

Nutrition:

Per serving: 250 calories (percent of calories from fat, 36), 5 grams protein, 35 grams carbohydrates, 3 grams fiber, 10 grams fat (2 grams saturated), 42 milligrams cholesterol, 345 milligrams sodium.