Mix the warm water,vinegar and honey,add the grapes and leave overnight to pickle.
When ready to make salad,remove grapes from pickling mix.
Cook the lentils in salted boiling water for 15-20 minutes,then drain and cool.
When cool,add the lentils,grapes,apple,onions,watercress and herbs to a salad bowl.
Whisk together the olive oil,vinegar and mustard,pour over the salad and season with salt and pepper. Toss gently and serve.
Serving suggestion: Pair with this rich,blood sausage dish.