Combine 1 cup (250ml) of the cider, the mustard, ginger and cloves in a large frying pan. Bring to a simmer. Add the sweet potato. Cover tightly and simmer until partially tender, 15 minutes.
Add ham steak; cover with sweet potato slices. Arrange apple wedges over the top. Cover and simmer until apples and potato are tender and ham is heated through, 10 to 15 minutes.
Using a slotted spoon, transfer ham, potato and apple to plate. Cover with aluminium foil to keep warm.
Blend cornflour and 1 tbsp cider in a small bowl. Stir a little of the hot pan liquid into the mixture until smooth. Add cornflour mixture into pan. Cook over medium heat, stirring, until slightly thickened, about 1 minute.
Divide ham, sweet potato and apple between 4 plates. Spoon on sauce from the pan. Garnish with spring onions.