Add the half cup olive oil, 4 cloves of garlic, onion, vinegar, paprika, cilantro, and sea salt to a zippered bag.
Slice your steak into 1/2 inch thick strips with the grain of the steak
Place steak into the zippered bag and marinade for 8-24 hours--the longer, the better
For the pesto, grind the basil, lemon juice, parmesan cheese, garlic, and olive oil in a food processor until it is fully pureed. Store in an air tight mason jar or container in the fridge until you are ready to use it.
Wash and pat dry your spinach leaves
Grill your steak to your preference.
Add steak to your bed of spinach, and add some pesto to the top; sprinkle with remaining Parmesan Cheese