Quit using the toaster oven and do it the right way.
^ ^ ^ this ^ ^ ^
And tortillas need grease
Barring that, go to the meskin store
( plenty here in SE Dallas) and buy
one of the round styrofoam doodads
designed for keeping tortillas warm.
Wash it out good and to sort of restore
some of the flexibility to your tortillas,
put a damp paper towel in the bottom
and 3-4 tortillas in and put the lid on
and nuke for about 12-14 seconds.
Lift the lid carefully because hot steam
will be rolling out when you open it.
The tortillas will also be somewhat
gummier than a proper fresh tortilla,
but it'll be flexible enough to make
your taco or burrito. It'll also be pretty
rubbery if you jack around and let
it get cold. It'll be tough as a piece
of hide if you try to heat it again, so
you'll have to toss it if you don't use
it right away after you take it out of
your styrofoam doodad.
Best off to buy fresh proper tortillas
made with grease