Preparation time: 20 minutes
Cooking time: None

1. Peel and dice the cucumber.
2. Rinse the tomatoes, quarter them and cut into small pieces.
3. Combine the tomato and cucumber in a bowl with the oil, vinegar, salt and pepper.
4. Halve the avocados. Remove the pits and mash the flesh with a fork.
5. Squeeze the juice from the lime and combine it with the mashed avocado.

Making the tacos

1. Divide the guacamole and tomato-cucumber mixture among the 12 tacos.
2. Add the chicken rillettes and serve.