Actually the lemon rind has a natural sweetness when eaten with the tart flesh inside. I use to eat whole the lemon wedges that came with my tea as a palate cleanser after the meal. Just don't try it with limes or oranges.
I found a nice little recipe for the mayonnaise that is traditionally spread on the bread.
Prepare 1 egg yolk and 100 ml of oil (vegetable oil, or olive oil if you like)
1. Separate the egg yolk and egg white. Keep the egg yolk
It should take about 30-45 minutes for 1 egg yolk. When finished, the sauce will have twice the volume of the original oil.