For the dressing, stir the mustard with the honey in a bowl until smooth. Then stir in the balsamic vinegar, add the olive oil and season with salt and pepper.
Drain the lentils well in a kitchen sieve, dice the tomatoes and cut the spring onions into rings. Add everything to the dressing.
Leave the bacon cubes in a small pan, allow to cool a little and fold under the lentils. Let the lettuce steep in the refrigerator until ready to serve.
To serve, divide the lentil salad on two plates, mash the cashew nuts in your hand and sprinkle over the salad. Halve the avocado, cut into cubes and add to the salad.