Warm up your outdoor grill or grill pan on medium flame.

To a small bowl, add the orange juice, oregano, 2 tablespoons lemon juice, 3 teaspoons garlic, 1 teaspoon salt, coriander, cumin, and chili powder. Mix well. Remove the stems from the portobello mushrooms and score the inside of the cap ever so slightly, making sure not to cut too deep. Add the mushrooms to a zip-top bag, and pour in the marinade. Seal the bag, and ensure that all mushrooms are coated with the marinade. Let marinate for 10 minutes.

While the mushrooms marinate, make your salsa by adding to a medium bowl, tomatoes, onion, black beans, jalapenos, ½ teaspoon salt, and 1 tablespoon lemon juice. Set aside.

Place the corn cobs and marinated mushrooms directly on the grill or grill pan. Pour the rest of the marinade in a small bowl, and use to baste the mushrooms while cooking. No need to butter or oil the corn. Using tongs, rotate/flip every 3 minutes, cover, and grill until the kernels are slightly charred & tender. Do the same with the mushrooms until they have nice char marks, and have released some of their water. Baste with every flip. This should take a total of 12 minutes. Remove to a cutting board and allow the cobs to cool.

Cut the kernels off the corn cobs, and add to the salsa mixture, mixing well.

Lay a bed of shredded lettuce in 4 MPOF containers, then divide equally the black bean salsa, avocado, black olives, and cheese among the containers. Top with mushroom carnitas. Store in your MPOF meal prep containers.