In a small bowl, whisk together the sweet soy sauce, light soy sauce, and tomato ketchup. Set aside.

Heat the vegetable oil in a large wok or skillet over medium-high heat. Add the minced garlic and shallots, stir-frying for about 1 minute until fragrant and lightly golden.

Stir in the chili paste and cook for another 1 to 2 minutes until the oil begins to separate from the paste, taking care not to burn it.

Add the shrimp and cook until they just turn pink, about 2 minutes. Toss in the cubed boiled potato and fried tofu, stirring well to coat the ingredients evenly in the spicy chili mixture.

Push the ingredients to one side of the wok. Crack the eggs into the empty space, scramble lightly, and let them set for 30 seconds before mixing them into the rest of the wok.

Add the yellow egg noodles, chopped choy sum, and the prepared sauce mixture. Toss everything vigorously over high heat for 3 to 4 minutes until the noodles are evenly coated, heated through, and slightly caramelized.

Turn off the heat and gently fold in the fresh bean sprouts so they retain their crispness. Serve immediately on individual plates with fresh lime wedges on the side for squeezing over the hot noodles.