Bring a pan of water with the vinegar to a gentle simmer. Crack the egg into a cup and gently slide it into the barely simmering water. Poach for three minutes and remove the egg with a slotted spoon.
Halve the avocado, remove the pit, and spoon the flesh in large pieces onto a plate. Drizzle immediately with the lemon juice to prevent browning, and season with salt and black pepper.
Flake the smoked trout into large pieces over the avocado and place the poached egg on top. Drizzle with the olive oil and scatter finely chopped chives over it.
Cut the egg open when eating so the yolk mixes with the olive oil to form a sauce. This breakfast consists almost entirely of fat and protein, exactly what your hormones need at the start of the day.