Place the pork in a large pot; pour enough water into the pot to cover the pork. Stir the soy sauce and lemon juice into the water. Bring the mixture to a boil for 5 minutes. Remove the meat and set aside. Discard the liquid.
Refill the pot with fresh water; add the pork liver and bring to a boil for about 5 minutes. Remove the liver and allow to cool; cut into bite sized pieces. Set aside.
Heat 3 tablespoons olive oil in a large skillet over medium-high heat; fry the potatoes in the hot oil until golden brown and cooked through, 7 to 10 minutes. Remove the potatoes to a plate lined with paper towels. Add 2 more tablespoons olive oil to the skillet and allow to get hot. Cook and stir the onion and garlic in the hot oil until fragrant, 3 to 5 minutes. Add the pork and pork liver to the skillet; cover and cook for 5 minutes. Stir the tomatoes into the mixture; cook together, stirring occasionally, another 5 minutes. Return the potatoes to the skillet with the green bell pepper. Season with salt and pepper. Cook and stir another 5 minutes.