Heat the oil in a large frying pan. Add the chicken, the red onion, the red and yellow pepper, the Cajun spice and the sweet smoked paprika. Fry on a high heat for around 8 minutes until the chicken is cooked completely through and the vegetables are soft. Remove from the pan and set aside.
Pop the lettuce cups on a large serving plate or tray and arrange so they are cup side up. Split the fajita mixture evenly between each of the leaves.
Top each lettuce cup with a small dollop of guacamole and salsa and then a teaspoon of soured cream. Finish with a sprinkling of fresh coriander leaves and serve.