Prepare whole portobello mushrooms by removing the stems and the dark brown undersides. You can use a spoon to scrape off any loose pieces. Rub approximately 1 TB of extra virgin olive oil into each side of each mushroom (2 TB per mushroom). You can add more EVOO if necessary to make sure the mushrooms are covered in oil.
Season the undersides of the mushrooms with salt, pepper, onion powder, garlic powder, cumin, and crushed red pepper. Heat a non-stick pan on high heat on your stove. Once the pan is hot, place the seasoned side of a mushroom down in the pan and cook until charred.
Flip the mushroom over and place a lid on the pan. Reduce the heat to medium and keep cooking until the mushroom softens and grills flat in the pan. Squeeze the lemon juice over the mushroom and cook until it’s darkened to your liking. Repeat steps 2-3 for each mushroom.
To make the chimichurri sauce, add whole cilantro leaves, chopped jalapeno, garlic clove, lime juice, and salt to a blender or food processor. Blend the ingredients until the cilantro is entirely broken down. You can add more lime juice to thin out the sauce if needed.
To make the citrus salad, chop baby spinach or a spinach and arugula blend and add it to a bowl. Toss the greens with extra virgin olive oil and a pinch of salt (and pepper if desired). Then, toss the greens once more with fresh lemon juice, orange juice, and chopped walnuts.
To assemble your plate, serve a mushroom with chimichurri sauce and approximately 1 ¼ oz salad. If you have extra chimichurri sauce, you can toss it with your salad too. When storing leftovers, keep the mushrooms separate from the salad.