If you are looking for some good bread in the Gangnam area, then I recommend Retro-Oven. It's kind of hidden, so the best way to find it is to go to their website http://club.cyworld.com/retrooven.
The chef was trained in Germany, so he makes rustic German style loaves that he has changed for the Korean palatte. The bread is fluffier and lighter than what you might find in Germany, but it doesn't mean the bread isn't good. It is very flavorful and I think it must have to do with the yeast that he uses. The bread has a sour-dough taste that is quite surprising.
They make fresh bread everyday starting at noon. They have chocolate croissants and cheese danishes at 12. At 12:30 they start serving hard loaves, pretzels, and olive loaves (recommended). They make the bread fresh everyday and they close when all the bread is gone or at 5pm.
I'm a big fan of their Laugen Croissant, which tastes like the perfect German soft pretzel. And their soft pretzels are amazing as well.
Here is their olive loaf and you'll find flecks of black olive. Really good and the bread makes a perfect gift.