Cook the lentils in salted water over a low heat for approximately 10 minutes. Drain well. Chop the parsley finely and stir through the lentils. Cut the feta cheese into cubes. Slice the water melon into pieces. Toast the mixed seeds in a frying pan without oil until golden brown.
Peel the shallot and chop into small pieces. Put the onions and all the remaining ingredients for the dressing in a small Byodo mustard jar and shake vigorously. Season with salt and pepper.
In a large storage/mason jar, begin with a layer of lentils and then add the olives, feta cheese and melon pieces in turn. Fill the jar up with lamb’s lettuce. Scatter the mixed seeds over the salad and close the jar for transport.
Before serving, shake the dressing in the mustard jar and drizzle over the salad.