Heat oil in a frying pan and fry red onion and plums over a high heat.
Add sugar, honey, vinegar, and lime juice to the pan and simmer for five minutes.
Transfer the relish to a bowl and allow it to cool.
Melt 15g of butter in a small frying pan.
Combine the beaten eggs with chopped ham and season with salt and pepper.
Pour the mixture into the pan and stir until the edges begin to set.
Cook over a low heat until completely set.
Slide the omelette onto a plate, slice into wedges, and serve with relish and parsley.