Prepare the beans, cook for approx. 12 mins. in boiling salted water until soft. Remove the beans, rinse in cold water, drain.
Combine the crème fraîche, mayonnaise and lemon juice in a small bowl, season. Finely chop the herbs, add to the bowl, mix.
Remove the lettuce leaves, wash. Drain and shred the tuna. Prepare the tortillas according to the packet instructions. Cover the tortillas with the lettuce leaves, beans and tuna, drizzle with the dressing. Fold in and roll up the tortillas.