As what other have mentioned. WB is off. You are shooting too close on some food shots. It does not look appetizing at all. Angle of the food can be improve. Composition is out as well. Too many stray lights which make too many reflections.
Should try to avoid direct flash. Most shots are underexposed.
You can use flash even at close range (provided your flash head can swivel at an angle).
If you are allow to use flash in the restaurant, by all means use it but aim at a different angle. If you are able to find a white wall will be better still so it can reflect to the food. When light is reflected off the wall and reflected towards your subject, it will be much softer lighting.