Place chicken strips in a resealable plastic bag with soy sauce, vinegar, paprika, cumin, black pepper, and garlic. Seal bag and shake up to cover chicken completely. Let marinate in the refrigerator for at least 15 minutes and as long as 24 hours.
Preheat the oven to 450 degrees F (230 degrees C). Arrange frozen fries in a single layer on a baking sheet.
Bake in the preheated oven until light golden, 20 to 25 minutes.
Meanwhile, heat oil in a large wok on high heat. Add the marinated chicken. Cook, flipping pieces occasionally, until mostly white on the surface, 4 to 5 minutes.
Add onion, bell pepper, and aji pepper to the wok with the chicken. Continue stir-frying until onions are slightly translucent but still hold their shape, 3 to 5 minutes.
Arrange baked fries on plates and place the chicken stir-fry on top.