The variety of food on Kiribati is limited. If a shipment of imported food has just come in, buy it now, as it won't last long! The variety and amount is increasing and improving all the time as is the number of supply boats that arrive.
While Western style products will always be slightly limited you will find that the basics are genrally available. A lack of fruit and vegetables really being the major concern.
The staple diet of the I-Kiribati is fish and rice and this is reflected in many of the eating outlets on Tarawa. It is always worthwhile trying the local sashimi which is stright from the ocean to your plate.
Western style meals are best found at the two hotels Marys and the Otintaai.
There is also a variety of Chinese restaurants.