Okay, we made this yesterday.
It was great! Even dh ate 3 of them!!!!
We will have this each time we have taco/tostada/burrito night.
I recommend you try it.
What I did:
I made mine in the crock pot on low for about 5 hours, I think I'll add a bit more water next time because it was all soaked up in 5 hours but some lentils were still a little crunchy, so six hours would be better, but in my crock pot it would have been burned by then.
I used beef bouillon cubes to give that beefy flavor. I may try vegetable some time and see if it still tastes good.
This isn't a meat substitute for sure, I mean I wouldn't try to trick anybody but as a different filling for tacos it's a great alternative.