In a large ziplock bag, add 1 flank steak. In a small bowl add ½ cup coconut aminos, 1 tsp salt, 1 tsp pepper, and 1 tsp garlic. Mix together with a fork until combined. Pour the marinade into the bag with the flank steak. Let this bag marinate in the refrigerator overnight for best taste.
Preheat oven to 425°F. Remove the flank steak from the marinade and place in between two pieces of parchment paper. Using a meat mallet, even out the thickness of the steak, beat until 1/2 inch thick.
In a blender, add the stuffing mixture, spinach, olive oil, seasonings, lemon juice, garlic cloves and sundried tomatoes. Blend until creamy.
Cover a baking sheet with a light layer of olive oil. Transfer the flank steak to the baking sheet. Top the flank steak with the sun-dried tomato mixture, spreading it out evenly. Sprinkle top of stuffing with ⅓ cup chopped onions and a little chopped spinach.
Roll the steak along the "grain" starting with the smallest end first. Roll the steak tightly. Using cooking twin tie the twine along the steak. I will tie in the middle and at each end. Tie tightly, but not too tight to where the stuffing is falling out.
Bake in the oven for 40-50 minutes, or until desired doneness.
Remove steak and allow to rest for 5-10 minutes before serving.