In South Korea a wide variety of foods can be found to satisfy just about every pallet. From hearty meat centered dishes to light vegetarian fare can be had.
Going Native. Of course the most widely available dishes are Korean style. Korean restaurants are ubiquitous and are found on every corner, everywhere. Koreans love meat and some sort of meat is included in almost every meal. However, as is with Korean tradition, side dishes are served and offer quite a selection of vegetables. If you are a frugal gourmet you can easily get by eating three full meals on about $5 - $10 a day. Shopping at a local grocery market for fresh ingredients and cooking at home you can get by on even less.
Western. When far from home comfort food can be as important as just about anything else you require to survive overseas. Finding your favorite dish or ingredients to cook with at home is, in general, very easy to do. Western style restaurants that offer anything from steak and potatoes to vegan breakfast omelets are available. For those who delight in a quick burger and fries, or a pizza delivered to your apartment South Korea has certainly embraced the fast-food culture. Just about every major fast food chain has representation in Korea. Specialty western style markets exist in larger towns which cater to western tastes and carry wide varieties of western food and ingredients. While western restaurants and markets exist you'll find that eating only which you are used to back home is possible but you will certainly pay more for doing so. Western ingredients are often more expensive than native Korean. Western style pubs abound in South Korea. Quite likely you'll find your favorite beer or spirit as well as some decent homespun "pub-grub". As well as pub sports like pool, darts, foos-ball, and large screen TV's displaying the latest soccer,football,basketball, rugby games, etc...
World Cuisine. In larger metropolitan areas, especially in and around Seoul, just about every culinary tradition is represented. From the Turkish kebob stand on the corner to 5 star European dining to Japanese sushi houses to fish and chips.
Coffee, Wine, Alcohol, and Tobacco Coffee shops have gained an incredibly strong foot hold in the Korean conscience. In just about every district in every town western style coffee shops have just about as much of a presence as Korean restaurants. Currently Starbucks is leading the charge and are quite present throughout the country. Second only to the presence coffee shops, wine has a popular following as well. Large upscale wine shops exist in just about every major town and city and offer a wide range of (mostly) imported red and white wines and spirits. Korea offers beer, strong traditional liqueurs and spirits for quite cheap. (Beware the small green bottle).
Tobacco in South Korea is readily available, relatively cheap and smoking is allowed in most public areas including most restaurants and bars, though South Korea is slowly embracing non-smoking ordinances and some establishments now offer smoke free areas. Top Korean and Western brands start at around $2 - $2.50