In a large nonstick skillet coated with cooking spray, brown ham on both sides; remove and keep warm.
For Hollandaise sauce, in a small saucepan, melt butter. Add flour and cook for 2 minutes. Add milk and stir until thickens, approximately 5 minutes. Remove from heat and stir in lemon juice; season with salt and pepper. Keep warm.
Fill large frying pan with water until it is within an inch of the top. Add vinegar. Heat and bring water to just under a boil.
Crack eggs into hot water. While water is heating, slice 2 English muffins in half and toast.
On each slice of toasted English muffin place a slice of ham and one poached egg, use slotted spoon to remove egg from water. Top with Hollandaise sauce.