I was in the Concord area today and drove a little out of the way to go to one of my favorite eats in the bay area. El Molino is located in the back of a strip mall on on Monument Blvd - about 2 miles off of 680. They have the most amazing, fresh, melt in you mouth tortillas out side of mexico. El Molino is truly a factory room with two huge machines cranking out both flour and corn tortillas.
Recently they expanded the waiting area with 5 table, a fresh juice bar, and a mexican cheese case. In addition to the tortillas, you can get very tasty Carnitas (I had a taco made with 3 torillas fresh off the machine and the carnitas, onions and cilantro - the juice dripping down my hands). You can also get fresh masa to make your own tortillas at home.
This place should be on your list if you live within 60 miles of the place. Don't be intimidated by the stark surroundings, the folks and customers are very nice - I even get to practice my broken high school spanish much to the amusement of the cashiers.
El Molino Tortilla Factory - 1500 F1 Monument Blvd ( at Reganti )