Begin by making the potato pancakes: Place the shredded potatoes and onions in a dish cloth and wring out all the water. Then, place them in a large bowl. Add the matzo meal, egg, salt, and pepper, and stir until combined.
In a large cast iron skillet, heat a quarter inch of oil on medium heat. The oil is hot enough when a teaspoon of the mixture starts to sizzle right away.
Form the potatoes into four patties. Place one or two in the pan at once. Flatten them out with the spatula, so they cook more evenly. Cook them on both sides until they are dark golden brown and crispy. Do not turn them more than once. If they start to brown too quickly, turn down the heat.
Drain the cooked latkas on a wire rack over a sheet pan. If you wish to reheat these later, reheat them on this rack at 350 degrees for about 15 minutes.
Also, make the vegetables: In a three quart saucepan, bring one inch of water to a boil. Add the asparagus, cover, and steam for six minutes. Drain and set aside. Cook the peas according to the package directions.
Also, make the Lemony Salmon: Melt half the butter in a nonstick skillet. Add the salmon and cook it to your desired doneness. Remove the pan from the heat. Add the lemon juice, lemon zest, and the rest of the butter. Stir unitl the butter melts.
Top each pancake with some of the veggies, and a slice of salmon. Pour some of the lemon butter over each salmon slice. Add a lemon slice on top of each slice, along with some scallions and red pepper flakes.