For the sour cream, I put 1 cup cashews with 1 TB vinegar (preferably something like sherry vinegar, ACV works too), maybe 1/4 tsp of salt (to taste), and enough water to get to the desired consistency ("as needed"). Blend in a high-powered blender like a Vitamix until smooth.
Can also inoculate with a yogurt culture and skip the vinegar and then ferment it if you have the time (use a yogurt maker and instructions, then ferment longer for a more sour flavor).
it tastes as good as it looks, too - takes some finessing to get a suitable nacho cheese flavor and to get the beef tasting like taco bell meat, but usually when I make this it tastes better than I expect it to. There have been a couple times where it didn't live up to expectations. Still trying to figure out exactly what contributes to the disappointment in those moments (but I suspect it's not adding enough seasoning to the beyond beef or cooking the beef too wet and not getting enough browning).
Another thing I like to do is melt some shredded violife (3 cheese blend or the american / cheddar cheese) onto the tostada before adding the sour cream and other toppings. I deep fry the tortilla, then put it on a tray and add the cheese and pop it into my convection oven with the broil setting for a minute or so.
I'm still a little freaked out by how meat-like the Beyond stuff is (at least as far as I can remember as it's been 25ish years since I had the real stuff). Normally I use Yves or TVP. I may have to go out and get some Beyond Beef just for this though. Thanks so much for posting it!
yes, it does a better job of emulating meat in some ways, but it's still mostly just TVP (and really overpriced TVP at that!).
The main advantage beyond beef has is through the use of methylcellulose, which is used to make the fat chunks. You could totally make this with your typical TVP taco meat, if you wanted more like beyond beef I would add more fats somehow, whether whole foods approach like avocado and cashews, or by making your own methylcellulose fat pucks in the freezer and shredding them into your TVP mix.