First, make the hollandaise sauce. Mix the ¼ tsp vinegar and the yolk from the separated egg in a small bowl or beaker. Using a stick blender, blend the egg yolk while slowly drizzling in the melted butter spread. Blend the sauce for another minute or so, until thick.
Heat a griddle pan over a high heat. Add the whole tomatoes for 10 minutes and cook until lightly charred. Meanwhile, bring a pan of water to the boil over a high heat, then reduce to a low simmer. Add the remaining vinegar and gently break the eggs into the water. Cook for 1½ minutes. Remove with a slotted spoon on to kitchen paper.
Wilt the spinach by piercing the bag several times and placing on a microwave-safe place. Microwave on full power for 1 minute. Set aside and leave to stand for 1 minute.
Meanwhile, toast the muffin halves. Top with the wilted spinach, smoked salmon and poached eggs. Pour over the hollandaise and serve sprinkled with the chives with the griddled tomatoes on the side.