Put the pork in a large saucepan and fry until brown, starting off over a medium-low heat and raising the heat as the fat begins to run. Scoop the pork out, leaving the fat behind.
Add the butter to the pan, and when it has melted, add the onion, celery and red pepper. Cook gently over a low heat until the onion is tender but not brown.
Add the rice, thyme and bay leaf to the pa