In a large bowl, combine the chicken, soy sauce, 1 tablespoon olive oil, salt, and pepper. Set aside to marinate while preparing the potatoes.
Bring a large pot of salted water to a boil. Add potatoes and boil for 8-10 minutes, or until the potatoes are slightly tender. Depending on the size of the potatoes, boiling times may vary. Drain water and set aside.
To a large skillet over medium-high heat, add 1 tablespoon of olive oil. Once hot, add the boiled potatoes and cook for 4-5 minutes, flipping halfway through, until golden and fork-tender. Transfer the potatoes to a plate and tent with aluminum foil to keep warm. Set aside.
To the same skillet over medium-high heat, add the remaining olive oil. Once hot, add the marinated chicken strips in a single layer. (Do not overcrowd the pan; work in batches if needed.) Reserve the marinade and set aside. Cook chicken for 1-2 minutes on each side, or until nicely browned and cooked to an internal temperature of 165°F.
Pour in the reserved marinade. Cook with the chicken until the liquid is reduced by half, about 1-2 minutes.
Add the sauteed potatoes and cowboy butter to the skillet. Toss to combine with the chicken and sauce. Cook for an additional 2-3 minutes, or until everything is heated through and the butter is melted. Season to taste with salt and pepper.
Remove from heat. Serve immediately, garnished with chopped parsley.