The night before you intend to cook this, you need to marinate the beef. Juice enough limes to cover the steak in lime juice and add in some salt, ground chipotle, black pepper, and ground coriander. Stir things up, submerge the beef, cover this up, and let it rest in the fridge overnight.
Shortly before you intend to eat this, prepare the salsa (it doesn't look nearly as attractive the next day. It will still taste fine, but hey, looks matter, too, right?). Peel and pit the mangoes, avocados, cutting small/medium sized chunks and putting them in a bowl. Squeeze in the lime juice, tossing well to prevent the avocado from discoloring. Peel and cut similarly sized chunks of jicama, and again, toss it well so that the lime juice helps keep the color looking good (brown chunks in salsa just doesn't catch your eye).
Also add in chunks of watermelon, a splash of rice wine, sugar, and a bit of freshly ground black pepper. Chop up some chipotles, cilantro, mint, tossing in as well. Finally, I sauteed some minced jalapenos in a dab of olive oil for about 3 minutes and garlic for another minute before adding this into the salsa. Taste it, season/spice it up as you see fit, and set aside.
Remove the steaks from the fridge and give them 30 minutes or so to come closer to room temperature. Fire up the grill and get it nice and hot so you can get a nice sear on the outside of those steaks. Then, season the meat with salt and pepper and simply grill to your desired doneness, flipping once (e.g. I like to figure something like 10 minutes total, but I am partial to a pink center), and then let it rest off of the heat for 5-10 minutes. With a sharp knife, slice the meat very thinly.
Finally, its time to put the tacos together. In a dry pan, toast the tortillas on high heat for ~30 seconds per side. Then, simply spread in a bit of the carne asada, a good few scoops of salsa, and crumble in some cotija. Wrap it up, serve with some black beans and some fried plantains, and most importantly, enjoy!