Preheat oven to fan assisted 180C / 200C / 400F / gas 6 and place sweet potato on one-half of a lined tray and the okra on the other half.
Keeping the vegetables separate, as they cook at different rates, season with salt and pepper and coat them with some oil.
Bake in the oven for about 20 mins for the okra and 25 min for the sweet potato making sure to turn them half way through cooking.
Heat some oil in a frying pan and fry the SPAM pieces for about 5 mins turning them so they are crispy on all sides and set aside.
Break the eggs into a bowl, season with salt and pepper and whisk the eggs with a fork until well mixed.
Heat an 8 inch frying pan over medium heat and melt a small knob of butter until melted and sizzling.
Add a quarter of the egg mixture, immediately tilting the pan so the mixture spreads evenly over the pan.
Cook for up to 2 mins until the omelette firms up, the edges are crispy but it still looks slightly wet on top (as the omelette will keep cooking for a little while).
Transfer the omelette unto a plate and serve immediately topped with a generous portion of roast vegetables, crispy spam, rocket and tomatoes.
Repeat three more times with the remaining eggs and each time serve as soon as the omelette is cooked.