Drain and rinse the lentils with cold water, then drain again. Place in a bowl with the lemon juice, balsamic vinegar, herbs, chopped red pepper and spring onions. Add the edamame or broad beans and cold salmon and toss to combine everything together.
Place in a sealed container, and keep chilled until lunchtime.
Keep a little of the salmon in the fridge for the next day, ready to toss into this substantial, chunky salad.