1.To make the dressing, crush the garlic and salt together with a knife. Transfer to a bowl and add parmesan. Slowly whisk in oil. Add shallot and verjuice. The dressing can be made several hours ahead; give it a good whisk before serving.
2.Prepare all the salad leaves, wash and spin-dry the cos, rocket and sorrel if using (there’s no need to wash witloof, just peel off outer leaves; it is better kept dry). Transfer to plastic bags lined with paper towels and refrigerate until needed.
3.Heat olive oil in a medium frying pan over medium heat and when hot, add bread cubes. Fry quickly until golden. Scoop out of pan with a slotted spoon and transfer to a plate lined with paper towels. Sprinkle with flaky sea salt. The croutons can be prepared a few hours ahead, but cover loosely with paper towels, or you’ll find every time someone goes past them, they’ll steal a few!
4.When ready to assemble the salad, tear salad leaves into smaller pieces and remove thick stems from sorrel. Arrange in a circle on a very large platter with the witloof. Halve the tomatoes and add to the platter with the croutons and cucumber. Scatter with herbs. Cut avocados in half, discard the stones and scoop out balls (you’ll have some avocado flesh remaining in the skins, scoop it out, transfer to a bowl, quickly mash with lemon juice, cover right on the surface with plastic food wrap and refrigerate – use for guacamole the following day) or halve, peel and slice avocados in the usual way. Scatter the salad with rocket.
5.Re-whisk dressing and transfer to a small serving bowl and place in the centre of the salad. Serve immediately with tongs and encourage everyone to spoon over their own dressing.
Get growing your own herbs and lettuces as soon as you decide to make this as it will save a considerable amount of dollars!