I would recommend you check out Airbnb Experiences. They have many experiences listed on their site for Mexico City like mezcal tasting and taco sampling. Just pick the one with good ratings. That way you don't have to travel all over the city looking for top notch taco places. But usually, you can spot a good taco place if there's a long line with "locals". If it looks like a lot tourists keep moving. Unfortunately, it's hard to find a lot of good taco places in just a few blocks since the city is so huge. I actually walk from my neighborhood over into a not so nice area (Balderas Metro Station) to get some good tacos.

But in the meantime, check out Netflix's series called Taco Chronicles. Try to find the first one they made about 4 years ago. It has a lot of good taco places in the city. Also, it depends on what type of tacos you like because some locations specialize in only certain types.