For the polenta: In a small saucepan over medium-high heat, bring the stock to a simmer. Then reduce the heat to medium-low. Next, slowly whisk in the cornmeal and continue whisking during the entire cooking process. Cook until the liquid has been absorbed, 5 to 6 minutes. Then add the cheese, again whisk, and then taste and season with salt and pepper. Hold warm until serving.
For the beef: Heat a large saute pan over high heat until the verge of smoking, and then add the oil; reduce the heat to medium. Sprinkle the steaks, both sides, with salt and pepper, and add to the oiled pan. Sear the steaks on the first side for 2 minutes, then flip and repeat cooking for additional 2 minutes. Once cooked, turn the heat off and add the butter and thyme. Allow the butter to brown, turning or spooning the butter over the steaks during the process, for 1 minute.
Remove the steaks and allow to rest for 2 minutes. Then portion the prepared polenta to the plates, top with seared tornadoes and then spoon over brown butter and serve.