How to Make It
In a blender or mini processor, combine the garlic, ginger, vinegar, ají amarillo paste, black pepper and 1 tablespoon of the soy sauce and puree until smooth. Reserve the lomo saltado sauce.
In a large pot of salted boiling water, cook the pasta until al dente. Drain well.
Meanwhile, in a large skillet, heat the oil. Add the ground beef and cook over high heat, stirring to break up the meat, until browned, 3 to 4 minutes. Using a slotted spoon, transfer the meat to a bowl.
Add the onion to the skillet and cook over moderate heat, stirring occasionally, until softened, about 5 minutes. Add the meat and tomatoes and cook over high heat for 1 minute, then add the remaining 2 tablespoons of soy sauce and boil for 1 minute. Stir in the chicken stock and lomo saltado sauce and bring to a boil.
Add the pasta and grated Parmesan to the sauce and toss to coat. Fold in the cilantro and season with salt. Transfer to a bowl, garnish with Parmesan shavings and serve.
Ají amarillo paste, a spicy Peruvian yellow chile paste, is available in many supermarkets and online at amazon.com.