Fry the onions in the butter for 5 minutes until soft.
Add the sausages and continue to fry until they start to brown and are cooked all the way through.
Add the tomatoes and simmer off the juices for 5 minutes.
Whisk the eggs together with the milk, herbs and seasoning and add the mixture to the frying pan.
Simmer on the heat until the egg starts to bubble and you can see that it has started to cook round the sides of the pan.
Transfer the frying pan to a hot grill and leave for roughly 5 minutes until the egg has cooked all the way through and the top is golden.
This will serve 2 on its own or 4 people if you are having it with toast.