Very finely chop the avocado, tip into a bowl and mix well with the lime juice. Roughly chop the tomatoes, then put them in a bowl with the shallot, Worcestershire sauce and tomato purée. Blitz with a hand blender until very smooth to make a coulis.
For the crab verrines, spoon half the tomato coulis into glasses then top with half the avocado mixture. Top with a little brown and white crabmeat.
For the Mexican verrines, stir the shallot, beans, coriander and cumin into the remaining tomato coulis, then season to taste with a the lime juice and chilli sauce. Spoon the avocado into glasses and top with the bean mixture. Will keep for up to one day in the fridge.
Dust the crab verrines with paprika. Top the Mexican verrines with ½ tsp yogurt, then dust with paprika to serve.