Well, thanks to Melanie and PolarBear's recommendations, I finally made it to 4 Hermanos! As promised, it was quite tasty, and you cannot beat the prices. A friend and I went there for lunch, and she had the chile verde burrito while I had the carnitas burrito. Burritos are a mere $2.50 apiece!! The burrito came wrapped up in paper and placed in a little basket like those mesh french fry baskets. We were very impressed with the looks of the tortilla--it looked homemade and was soft and pliable and just the right thickness. My burrito was packed with carnitas and freshly chopped tomatoes and cilantro. The carnitas was flavorful and kind of greasy-crunchy in a good way, if that makes any sense. My friend thought the chile verde was very good, with the meat trimmed of excess fat. Also, the salsa is very tasty. It is of the non-chunky variety (gee, isn't that descriptive?)
4 Hermanos are supposedly open daily, though my husband and I tried to go there on a Tuesday evening and found it closed! Luckily, there are many other dining options in Paso Robles for such instances.