In a small bowl, combine the peanut butter, soy sauce, and sesame oil. Stir together well. Set aside. Chop the green onion, separating the white part from the green.

Bring a large pot of water to a boil. Add the ramen noodles and cook just until tender, about 2–3 minutes. Reserve 1/2 cup of the pasta water, then drain and set noodles aside.

Heat a skillet over medium heat. Once warm, add the olive oil and the whites of the onion, cooking for 30 seconds before adding the sauce and continuing to cook, stirring constantly, for 1 minute.

Add the cooked noodles to the pan. Toss together with the sauce until the noodles are coated. Add a little pasta water at a time to loosen the sauce, allowing it to coat the noodles evenly. Remove the pan from the heat.

Cut limes and squeeze over the pasta (3 tablespoons). Toss with the pasta. You can serve with additional lime slices.

Plate the pasta and sprinkle with the green parts of the green onions before serving.