Whisk all ingredients together, and season with salt and pepper.
Wash tomatoes and cut them into slices and wedges. Arrange them on plate along with feta cheese, olives, capers, fresh basil and arugula. Season generously with the vinaigrette.
Mix salt and sugar together. Squeeze out a couple of lemons. Quarter remaining lemons but not all away through. Stuff each lemon with the salt-sugar mixture. Pack lemons into jars alternating with more salt-sugar mixture and juice. Seal and refrigerate the lemons for at least 2 weeks. Best after 3 months and can be kept for more than a year. Lemon confit can also be canned and sterilized; they'll keep for years at room temperature. To use the cured lemons, remove the flesh and scrape the remaining white part saving the peel only. Rinse well and cut into fine dices.