Step 1

Blanch the green beans in a pan of boiling salted water for 2-3 minutes until tender. Drain and refresh.

Step 2

Put the chopped red onion in a sieve and run under cold water to remove some of the harsh flavour of raw onion.

Step 3

Put the butter beans and the kidney beans in a bowl and stir in the green beans, onion, cherry tomatoes, rocket and tuna.

Step 4

For the dressing whisk the mustard, honey, and the lemon zest and juice. Season, then whisk in the olive oil. Toss with the salad.