The one you made looks excellent, I cook them quite a bit but I usually just put cheese inside. If I’m filling it with veggies or chicken, I always cook that stuff first.
If you try and go low and slow, you’re going to end up with a hard crackly tortilla, cooking quick keeps it chewy and crisp on the outside.
On my electric stove, the dials go from 1-10 and I find that for my stove, preheating my cast iron pan with the burner on 4 keeps it from burning but cooks it pretty quick.