Even my mushroom hating High School Guy ate and enjoyed several beef & mushroom tacos after I made him try a bite. "You're right, mom! That's so weird -- you can't even taste them." So take it from him, and give this a try for yourself!
Brown ground beef over medium-high heat in a large skillet, stirring occasionally and breaking up as you go.
Meanwhile, pulse the mushrooms, onion, and garlic in your food processor until minced and nicely combined. (You'll need to do this in a couple of batches.)
When the meat is mostly browned, stir in the mushroom mixture. Cook until completely browned, then drain the meat & mushroom mixture and return it to the pan.
Stir in spices and tomato sauce. Reduce heat to low and simmer for about 7 minutes, stirring occasionally.
Serve with your favorite taco fixings.
Baby bella mushrooms will be easier to hide and add a little more meaty umami flavor, but either white or bella mushrooms will do. I used 8 oz of each in my tacos, since that's what I had on hand today -- or you could ease into the meat-and-mushroom idea with 8 oz total, then up the mushroom-to-meat ratio next time if no one notices.
Sneaky Ground Beef & Mushroom Tacos from Mashup Mom: https://www.mashupmom.com/sneaky-ground-beef-mushroom-tacos/