Blanch the spinach: Bring a pot of water to a boil. Once boiling, add 8 oz spinach and blanch for 1 minute. Remove with a slotted spoon, transfer to an ice bath, and leave to cool for 2 minutes. Drain and squeeze well to remove any excess water. Put on a plate lined with paper towels and set aside.
Steam the vegetables: In a large pot, fill it with 1-inch of water, put the steamer basket inside and bring to a boil. Once boiling, reduce the heat to medium and add potatoes to the steamer basket. Cook for 15 minutes. Then add 10 oz button mushrooms and 10 oz asparagus to the steamer basket and cook for another 10 minutes. Once cooked, transfer to a large plate and set aside.
Make Hollandaise sauce: Bring a small pot of water to boil then simmer over medium heat. Place a glass or metal bowl that fits the pot on top, making sure that the water doesn’t touch the bowl. Add 3 egg yolks, 1 tbsp white wine, 1 tsp lemon juice, and 1/8 tsp salt to the bowl. Whisk vigorously for 2 minutes. Add 1 1/2 tbsp unsalted butter cold and continue to whisk until fully melted into the sauce (about 1 minute.) Add ½ tsp chopped parsley and whisk in. Turn off the heat, remove the bowl from the boiler, and set aside.
Toast English muffins: Slice 4 English muffins in half. Bake the muffins in a 375°F oven for 2 minutes. (You can also toast each slice in a toaster.)
Poach the eggs: In a pot of water, add 1 tbsp white wine and 2 tbsp vinegar. Bring the water to a boil and then reduce the heat to medium. Use a spoon to swirl the water, creating a vortex. Add one egg, cook for 2 minutes, and remove from the water with a spoon. Transfer the poached egg to a dish lined with a paper towel to absorb excess water. Repeat with the remaining eggs.
Serve: Put a muffin slice on one side of a plate, put spinach and mushrooms on top, then place 2 eggs over the veggies, spoon the sauce over the eggs, and put the other muffin slice on top. Place asparagus and potatoes on the other side of the plate. Garnish with the remaining parsley and ground black pepper.