Grate the potatoes using a box grater or food processor. Place them in a clean kitchen towel and squeeze out as much moisture as possible.
In a large bowl, combine the grated potatoes, onion, beaten egg, matzo meal, kosher salt, and black pepper. Mix well.
Heat about ¼ inch of vegetable oil in a large skillet over medium-high heat.
Scoop portions of the potato mixture into the skillet and flatten slightly. Fry until golden brown and crispy, about 3–4 minutes per side.
Transfer cooked latkes to a paper towel-lined plate and keep warm.
To make the hollandaise sauce, place egg yolks, lemon juice, and salt in a blender.
Blend while slowly drizzling in the melted butter until the sauce becomes smooth and thick. Set aside in a warm place.
Fill a saucepan with water and bring to a gentle simmer. Add a splash of vinegar.
Crack each egg into a small bowl and carefully slide it into the simmering water. Poach for 3–4 minutes until the whites are set and the yolks remain soft.
Remove eggs with a slotted spoon and drain briefly.
Assemble the Latke Eggs Benedict Recipe by placing two latkes on each plate.
Top each latke with smoked salmon, a poached egg, and a generous spoonful of hollandaise sauce.
Garnish with fresh chives and diced red onion before serving.