Put the avocado flesh, eggs and the milk in a blender. Pulse for a few seconds then add the flour, baking powder, oil, salt and add more milk, if needed, to have a thick, but pourable batter.
Heat the waffle maker. Once it’s hot, spoon in the batter and seal. Following the machine instructions, cook the waffles for about 5 minutes - they should be golden and crispy on the outside, soft inside. You should be able to get 3 or 4 waffles from the mixture (depending on the size of your machine).
Meanwhile, make the salsa: chop the tomatoes, bell pepper, spring onion, chilli (if used) and herbs, then put them in a mixing bowl. Add the garlic, oil, lemon juice and a pinch of salt. Combine, taste and adjust to your liking.
Serve the waffles warm or at room temperature with the salsa.