Place cubed potatoes in medium pot with chicken bouillon; add enough cold water to cover potatoes completely. Place pot over medium-high heat; bring water to boil then reduce heat to medium-low. Simmer until potatoes are completely tender, about 20 minutes. Drain potatoes; transfer to same pot. Using fork or potato masher, lightly mash potatoes; set aside.
Meanwhile, heat oil in large skillet over medium-high heat. Add onion and pepper; cook, stirring occasionally until soft, about 8 minutes. Add scallions, cilantro and garlic. Cook, stirring, until scallions begin to soften, about 1 minute. Stir in tomatoes; cook until water from tomatoes evaporates, about 4 minutes more. Add ground beef and pork; season with Sazón and Adobo. Cook, breaking up meat with wooden spoon until browned and cooked through, about 8 minutes. Transfer pork and beef filling to large heat-proof bowl and stir in mashed potatoes; let sit until steam subsides. Refrigerate until cold. (Note: Filling can be stored covered in refrigerator for up to 5 days.)
Add masarepa to medium bowl. Stir in water, oil, Sazón and salt until well combined. Using hands, knead dough until soft and smooth. Form dough into large ball; cover with damp paper towels and let rest 20 minutes. Divide dough into 30 portions; roll into small balls (keep balls of dough covered with damp paper towels). Using tortilla or empanada press lined with plastic wrap, press ball into 4" diameter circle. Remove top plastic and spoon 2 tsp. cooled filling in center of dough. Using bottom plastic to help, fold dough in half to form half-moon shape; peel back plastic. Seal edges by pressing with fingers. Or, using open side of drinking glass, press firmly on edges of dough to seal (remove any overhanging scraps of dough). Repeat with remaining dough and filling to make 30 empanadas.
Heat 2" oil in large, heavy pot over medium-high heat until oil registers 350°f on deep-fry thermometer. Alternately, heat oil in deep fryer to 350°F. Fry empanadas in batches until dough is crisp and filling is hot, about 3-4 minutes per batch. Transfer empanadas to paper towels to drain. Serve warm with limes and ají.