Special equipment: blender
In a medium bowl combine the soy sauce, sesame oil, mirin, sugar and 2 tablespoons of the minced garlic. Add the sliced beef and toss to make sure all the beef is coated in the marinade. Cover and marinate in refrigerator for at least 30 minutes or up to overnight.
Heat 3 tablespoons of the canola oil in a medium saucepan set over medium heat. Add the onions and saute until softened and translucent, 3 to 4 minutes. Add the remaining 2 cloves chopped garlic and continue to saute for 1 to 2 minutes. Add the miso paste and cook another 2 minutes. Add the beef broth, 3 tablespoons of the butter, cayenne and lime juice. Stir until combined and bring to a gentle bubble, 2 to 3 minutes. Place the liquid in a blender and blend to emulsify.
Bring a large pot of salted water to a boil.
Remove the beef from the marinade and place on a paper-towel-lined plate. Pat dry. Heat 3 tablespoons of the canola in large saute pan set over high heat. Sear the beef until browned and the edges are caramelized, 3 to 4 minutes. Reserve on a plate.
Heat the remaining 3 tablespoons canola oil in a large saute pan set over medium heat. Add the kale and saute until wilted, about 3 minutes. Add the snow peas and scallions and saute for 3 to 4 minutes.
While the vegetables cook, add the pasta to the boiling water and cook until al dente, about 5 minutes. Drain the pasta and reserve the cooking water. Pour the pasta into the pan with the vegetables. Add the sauce from the blender and the remaining 3 tablespoons butter, plus 1/2 cup of the pasta water. Flip and stir the pasta over medium heat until the liquid thickens enough to coat the pasta and vegetables, 2 minutes. Transfer the pasta to serving bowls and serve with a few pieces of beef arranged alongside the pasta.
When blending hot liquid, first let it cool for five minutes or so, then transfer it to a blender, filling only halfway. Put the lid on, leaving one corner open. Cover the lid with a kitchen towel to catch splatters, and pulse until smooth.