Bring a large pot of water to a boil and cook the udon noodles according to the directions on the package. Drain.
Meanwhile, in a small bowl, mix the chicken stock, soy sauce, vinegar, samba olek, and sesame oil. Set aside.
Heat the olive oil in a large sauté pan set over medium-high heat. Add the garlic and cook 2-3 minutes, or until it begins to soften. Stir in the ginger and cook 1 minute. Add the pork and cook for 5 minutes, or until nearly cooked through. Pour off and discard and liquid that has accumulated in the pan.
Push the pork to one side of the pan and add the bok choy to the other side. Cook 2-3 minutes, until the bok choy begins to wilt. Reduce the heat to medium and add the sauce. Cover and cook 3-5 minutes, or until the pork and bok choy are cooked through.
Mix in the cooked udon noodles and top with scallions.
Notes
Look for fresh noodles in the produce section of bigger supermarkets or at Asian markets. They cook quickly and have an amazing chewy texture that I prefer to dried noodles.