Two diners suffered food poisoning and others suffered symptoms after eating a dish containing the meat at the restaurant.
Luscombe was fined £4,434, ordered to pay £5,284 costs and a victim surcharge of £120.
Luscombe admitted serving food on the premises that was unsafe as it had been inadequately cooked and failing to implement and maintain legally required food safety procedures, including those for the safe cooking of high risk foods.
Magistrates heard South Oxfordshire District Council, the environmental health authority, was asked to investigate after a member of the public suffered campylobacter food poisoning after eating at the restaurant.
Environmental health officers carried out an immediate unannounced inspection and found that the diners had been offered a set menu including calves’ liver for the main course.
They found the calves’ liver had been cooked at too low a temperature.
The restaurant was found to have no protocol to ensure high risk items, such as liver, were cooked according to recommendations from the Food Standards Agency.
It also failed to complete required monitoring records for almost three months, meaning it was failing to meet its legal requirements for food safety.