Place the gammon steaks on the upper rack of the halogen oven.
Mix together the mustard, honey, lemon juice and tarragon in a bowl and season with a little salt and pepper. Brush a little of the mustard mixture over the steaks.
Set the temperature to 200°C (392°F) and cook the steaks for 5 minutes. Turn them over and brush with the remaining mustard mixture. Cook for a further 5 minutes or until the steaks are cooked through. Serve with chunky chips, a leafy salad and apple sauce.