Drain the kidney beans and chickpeas, rinse through with water and leave to one side to drain. Drain the mussels too.
Peel and finely dice the onion. Dice the tomatoes, cucumber and celery into approximately the same size.
Chop all the fresh herbs. The measurements here don’t have to be exact and the combination of herbs can be varied to suit your taste – but don’t skimp on the herbs!
Make the dressing: Crush the garlic into a bowl and whisk in the olive oil and lemon juice. Season well.
Place the beans, onions, tomatoes, cucumber, celery, mussels and fresh herbs into a large bowl. Pour over the dressing and mix well to combine. Taste and add more seasoning or herbs if desired.
Serve with toasted pitta bread on the side.