Slice the onions as thinly as possible (ideally using a mandolin). Place in a ziplock bag or small Tupperware container.
In a small bowl combine the vinegar with the salt and sugar. Stir well until the sugar and salt are completely dissolved. Pour over the onions. Cover and place in the fridge for minimum 20 minutes.
To Make the Hummus
In a small frying pan, add the olive oil and bring to a medium heat. Add the garlic and fry until starting to brown. Turn off the heat and allow to cool for a few minutes.
In a high speed blender, add the butterbeans. On top of the butter beans pour the oil and garlic from the pan. Add the rest of the ingredients and blend until smooth. If too thick, add another tbsp lemon juice or water.
Arrange the chopped veg around the hummus and pickled onions.