On a large board, trim and finely chop the carrots and celery, finely chop the tomatoes, then separate and finely chop the lettuce leaves.
Once everything is fairly fine, start mixing it up and chopping some more.
Crumble over the feta, if using, then pick and roll the mint leaves like a cigar and chop into the salad.
Make a well in the middle, add the mustard, balsamic vinegar, oil and a pinch of sea salt and black pepper and mix together. Then start mixing the salad into the dressing, chopping and mixing as you go. Or, you could make the dressing by mixing all the ingredients in a jam jar, ready to dress the salad at the table.
The brilliant thing about a chopped salad is you can use anything fresh, crunchy and delicious – think broccoli, white or red cabbage, cucumber, peppers, whatever you fancy.