Begin by grating the russet potatoes and yellow onion using a box grater or food processor. Soak the grated mixture in lightly salted water for 20-30 minutes, then drain thoroughly and squeeze out excess moisture.

Combine the drained potato and onion mixture with a beaten egg, matzo meal, kosher salt, and ground black pepper in a bowl. Stir until evenly moistened.

Heat vegetable oil in a skillet over medium heat to create a 1/4-inch depth. Ensure the oil shimmers and is hot enough for frying.

Spoon heaping tablespoons of the latke batter into hot oil, frying in batches for 6-10 minutes on each side until golden brown. Keep latkes warm in a low heat oven.

In a separate saucepan, bring water to a gentle simmer and add a splash of vinegar. Crack each egg into a ramekin, then slide them into the simmering water to poach for 4½ to 5 minutes.

Blend egg yolks, fresh lemon juice, and salt until airy. Slowly drizzle in melted butter until the sauce thickens. Keep warm in a double boiler.

To serve, place a crispy latke on each plate, top with smoked salmon and a poached egg, and drizzle with hollandaise sauce. Garnish with chives and red onion.