Frozen pollock fillets are usually used for making jeon in Korean cuisine. Before cooking, thaw out these rock hard solid frozen pollack fillets for about 20 minutes at room temperature. Then you can slice them thinly very easily.
My cookbooks
Which to get? my first book has all the recipes for all the essential Korean pastes and sauces, but my second book Maangchi's Big Book of Korean Cooking has more recipes. Both are best sellers and either one is a good choice if you want to learn Korean home cooking.