In small bowl, stir together vinegar, soy sauce, sugar and hot yellow pepper paste; set aside.
Season beef with adobo. Heat 1 tbsp. oil in large wok or large non-stick skillet over medium-high heat until oil shimmers. Add beef; cook until dark golden brown on all sides, about 3 minutes; set aside. Heat remaining oil in skillet. Add onions; cook until crisp-tender, about 5 minutes. Add garlic; cook until fragrant, about 30 seconds more.
Transfer beef to pan; pour in reserved vinegar mixture. Using wooden spoon, scrape up any particles stuck to bottom; stir in cooked potatoes and tomatoes until coated in sauce.
Transfer beef and potato mixture to plate; sprinkle with parsley. Serve with warm rice.
The key to the perfect stir-fry – meat that browns quickly and vegetables that retain their crisp bite: a hot pan. To ensure your pan stays hot, add the meat and vegetables in small batches (about 1 cup per batch). This prevents the temperature of the pan from dropping and encourages a dark caramelized coating on meat and crisp – not soggy – veggies.