Mix the first 6 (or 7 if using jalapeno) ingredients in a large bowl or gallon zip lock bag. Set aside 1/2 cup of the marinade to use later.
Remove any white connective tissue from the meat then cover it with plastic wrap and pound it with a meat mallet (or other pounding object) to tenderize it. Poke it all over with a fork to allow the marinade to get into the meat.
Add the steak to the bowl or bag with the marinade. And marinate for at least 1 hour (up to 8 hours).
In a bowl, combine the marinade ingredients with the steak.
***See notes below for stovetop and grill instructions.
To Cook in the Oven: Turn the oven broiler on high. The oven rack should be high up so it's about 4-6 inches below the heating element. Give it about 5-10 minutes to heat up.
Cover a broiler pan or metal baking sheet with foil, then place the flank steak on it (try to minimize how much marinade you put with it). Put it in the oven just under the heating element.
Cook it for about 4-6 minutes, then use tongs to flip it over and cook an additional 4-6 minutes or until the internal cooking temperature reaches 135 degrees Fahrenheit (for medium-rare) or 145 degrees Fahrenheit for medium. Cooking times will vary depending on thickness so watch it closely! For reference, my flank steak was about 1" thick. If yours is thinner, it will probably take less time to cook. *Note, you may notice some residual marinade in the pan start to carmelize, burn and create smoke while the meat is cooking. If this happens, it can help to turn the broil setting down to low for the rest of the cooking time (you may just have to leave it in a bit longer).
While the meat is cooking, make the mango salsa.
Take the meat out of the oven and allow it to rest for about 10 minutes before slicing it.
Start to assemble your bowls using cauliflower rice, mango salsa, cucumber, avocado, radishes, and lime wedges. *Leave some space in the middle for the meat.
Transfer to steak to a cutting board and slice it against the grain into thin strips.
Place several strips of meat in each prepared bowl and drizzle with the marinade reserved at the beginning of the recipe (or use it for dipping).
**While this recipe uses the oven in the main instructions (I used the oven out of necessity), I'd recommend cooking the meat on a grill if you have the option (see instructions below), mainly because both oven and stovetop methods produce a fair amount of smoke. Minimize Smoke While Broiling: If the smoke gets to be excessive, turn the broil setting down to low or even take it off the broil setting and set the oven to bake at about 400 degrees Fahrenheit for the rest of the cooking time (you may just have to leave it in a bit longer than planned). Keep track of the internal cooking temperature with a meat thermometer as you go.*Glass Cookware is not recommended for broilingGrill Instructions: Heat the grill to medium-high and cook the steak for 4-7 minutes per side or until internal temperature reaches 135 degrees Fahrenheit (for medium-rare), 145 degrees Fahrenheit for medium. Stovetop Instructions: *Will need to turn on range hood fan over the stove as this does create some smoke. Heat a large pan over medium-high heat and add 1-2 tbsp of coconut oil or oil of choice. Cut the meat into 3-4 smaller chunks- may need to cook in two batches depending on the size of the pan. Cook for 4-7 minutes on each side or until internal temperature reaches 135 degrees Fahrenheit (for medium-rare), 145 degrees Fahrenheit for medium. If the meat starts to burn on the outside before the inside is cooked, turn the heat down a bit.For the Marinade: I found that I prefer avocado oil or a lighter olive oil (not extra virgin) simply because the flavor of EVOO sort of interferes with the other flavors. If you only have EVOO, it’ll be fine but a milder flavor oil is recommended if you have it.