Place frozen peas in a bowl with the clove of garlic, and pour on enough just boiled water to cover. Set to one side.
Grate the carrots, peel (if necessary) and finely slice the beetroot.
Drain the peas and clove of garlic and place in a blender with the extra virgin olive oil. Blend until smooth, adding a little hot water if necessary to loosen, and then season to taste.
Assemble the sandwiches, first spreading the bread with the pea purée, then adding layers of carrot, beetroot and the rocket or watercress.
Finish with a sprinkle of sea salt and black pepper if you like.
Notes
To get ahead, the pea purée can be made in advance and stored in the fridge for up to 3 days.
