Begin by grating 2 large russet potatoes and 1 medium yellow onion into a large bowl. Soak the grated mixture in salted water for up to 1 hour.

Once soaked, drain the potato and onion mixture in a colander, then using a clean kitchen towel, squeeze out as much moisture as possible.

In a large mixing bowl, combine the drained potato-onion mixture with 2 beaten eggs, matzo meal or all-purpose flour, and season with kosher salt and ground black pepper to taste.

In a skillet or large frying pan, heat about 1/4 inch of vegetable oil over medium-high heat until shimmering.

Form the latke mixture into 3-inch rounds and carefully place them into the hot oil. Fry for approximately 6-10 minutes on each side until golden brown.

In a wide saucepan, bring water to a gentle simmer and add vinegar. Crack the eggs into small cups, then gently slide them into the water one at a time.

In a heatproof bowl, whisk together 2 egg yolks and the juice of half a lemon. Gradually whisk in 1/2 cup of melted unsalted butter until the sauce thickens.

To serve, place one crispy latke on a plate, layer it with smoked salmon if desired, then top it with a poached egg. Drizzle hollandaise sauce over the egg and garnish with chives and red onion.