Brush a large non-stick frying pan with sunflower oil, using the tip of a pastry brush. Place the pan over a medium heat and add the bacon. Cook for 2 minutes until lightly browned, then turn and dry-fry on the other side for another 3 minutes.
While the bacon is cooking, half fill a medium non-stick saucepan with water, add the vinegar and bring to the boil. Turn the heat to low, so the water is only just bubbling.
Crack the eggs into the water, 1 at a time, spacing them well apart. Cook for 2½ minutes. Te eggs should rise to the surface within a minute. If the egg white sticks to the bottom of the pan, lift it gently with a wooden spoon. Alternatively, you can use a hob-top egg poacher, lightly greased with sunflower oil.
Add the tomatoes to the pan with the bacon and season with plenty of black pepper. Cook the tomatoes for about a minute until just beginning to soften, turning them once. Put a small pile of watercress on each plate.
Place some bacon and tomatoes on the plates and drizzle with a dash of balsamic vinegar. Take the eggs out of the water with a slotted spoon and place them on top. Season with a little more pepper and tuck in right away while it’s all lovely and hot
