Note: The only tricky part of this dish is smoking the crayfish. I used a domestic smoker that you should be able to find at a good hardware or kitchenware store. Follow the instructions with your smoker and you shouldn't have any problems.
Bring the smoker to heat, then place in the crayfish tails and smoke over a moderate heat for 10 to15 minutes. To check if the tails are ready, take 1 piece out of the smoker and using a sharp knife, insert it into the thickest part of the tail. The flesh should be opaque in color, neither raw nor totally white. Take the tails from the smoker and leave to cool. If the tails aren't quite ready, just put back in the smoker and smoke a little more. The smoker will generate heat, so the hotter the smoker, the quicker the tails will cook. Once the crayfish are cool enough to handle, pry the meat from the shells and cut into thick chunks.
Place the salad leaves in a large bowl and scatter on the crayfish, the tomatoes and the cheese. Whisk the avocado oil and the lemon juice together, season well, then pour dressing over the salad, and gently toss together. Eat immediately.