If your tortilla strips are still soft after flipping them and baking them on the second side, it is likely that the tortilla strips were placed too closely together and/or there are too many on the sheet. Remove any fully crispy tortilla strips (to avoid any burning) and replace the remaining tortilla strips back into the oven for 1-2 minutes. Check their crispiness by testing to see if one or two in the middle snap when bent. If they do not, repeat this process (only baking for 1 additional minute each time) until tortilla strips are fully crispy.