Because I've found a way to make crisp, oil-free tortilla chips (and tostada shells) in the microwave, I haven't pursued baking them in the oven. It seems I remember having tried this in the past, and not getting the same good results I get from the microwave. But the problem with the microwave is you can only process one tortilla at a time, and each tortilla takes about two minutes. So, in the spirit of adventure, I decided to try the "Tortilla Chips" (page 5) to see if anything had changed. The recipe as written calls for the tortilla chips to be brushed with oil, but I omitted this step in order to make them McDougall Plan friendly.
I cut the tortillas into triangles, placed them on cookie sheets (no oil or parchment paper required), and sprinkled some salt free spicy seasoning on top. I baked the first batch for 12 minutes (the recipe calls for 8-10), and let them rest for several minutes to crisp up, but they were still kind of soft and chewy. (I remember now - this was the same problem I experienced all those years ago!). The next batch I left in for 14 minutes, checking often after 10 to make sure they weren't burning (it smelled like they might be), then I turned off the oven and let them sit inside with the door closed for 2 more minutes. These came out crispy, but kind of dry.
I'm figuring it's the lack of oil that's causing the chips to be either, too soft and chewy, or too dry. This may just be the way it is with oil free oven baked chips. For now, I think I'm going to stick with the microwave method I have devised, even though it takes a lot longer if making more than a few chips.