Place the ham in a large roasting dish with the garlic, oranges, onion and thyme. Pour in the chicken stock then cover with foil and cook per instructions in my Apricot Apple Glazed Ham recipe.
Make the glaze: Once the ham is cooked, remove from the oven and allow to rest for 10 minutes.
Carefully slice off the rind and score the fat with a sharp knife.
Transfer 1 cup of the ham's cooking liquid to a saucepan and add the brown sugar, orange juice, lemon juice and a generous pinch of salt.
Bring to a simmer over medium-high heat and cook for 10 minutes or until the glaze has reduced by half.
Transfer the ham to an oven-proof dish then pour over half of the glaze.
Place the ham in a 220ºc/430ºF oven and allow to caramelize for 15 minutes, spooning over the remaining glaze every 5 minutes until the ham is glossy and caramelized.
Remove the ham from the oven and allow to rest for at least 20 minutes. Slice with a sharp knife and serve.