Place shredded potatoes in a microwave safe bowl and microwave for 3 minutes. While potatoes are heating, pour 3 Tablespoons vegetable oil into a 12 inch cast iron or non stick skillet. Heat the oil over medium to medium high heat.

Remove the potatoes from the microwave and spoon 1 cup of the potatoes into the skillet. Repeat with another cup of potatoes and flatten to each mound of potatoes to make a patty. Cook hash browns for 5 minutes.

While hash browns are cooking, drain and rinse the beans. Combine beans with a large handful of cilantro, juice of 1 lime, cumin, garlic paste and salt in the bowl of a mini food processor. Process until smooth. Set aside.

Turn the potato patties over and cook for another 5 minutes. Dice the avocado and slice the green onions.

Remove the patties from the pan. Add the remaining oil to the pan and repeat with the remaining potatoes.

Spread 2 Tablespoons of the black bean mixture on each patty and top with romaine, salsa, cheese, avocado, green onions and sour cream if using.