In a medium saucepan over high heat, bring the broth to a boil. Reduce the heat to very low, adjusting to keep the broth just below a simmer.
In a large saucepan or small stockpot over medium heat, warm the oil. Add the onion, salt, and pepper and cook, stirring occasionally, until the onion is very soft, 6 to 8 minutes (adjust the heat to avoid browning). Add the rice and stir until the grains are coated with oil. Add the wine and cook, stirring, until absorbed. Ladle in enough hot broth to barely cover the rice, about 1 1/2 cups.
Stir constantly until almost all of the broth has been absorbed, adjusting the heat to maintain a simmer. Continue adding broth, about 1/2 cup at a time, and stirring almost constantly, adding more broth when almost all of the previous addition has been absorbed.
After 15 or 20 minutes, taste the rice for doneness. It should be tender but firm, with no chalkiness in the center, and the overall mixture should be slightly looser than you would ultimately like it (the final addition of cheese will thicken it). If it’s not done, continue cooking, adding broth, and stirring until the rice is done (you may not need all of the broth).
Remove the risotto from the heat and stir in the radicchio, steak, and cheese. Add salt and pepper to taste.
Serve the risotto hot, drizzled with the vinegar. Pass additional cheese and vinegar at the table.Copyright Jill Silverman Hough. All rights reserved. www.jillhough.com.