Radicchio has an assertive flavor. It pairs wonderfully with sweet and rich sauces. It becomes even more complex, developing a rich aroma with subtle bitter bite, when gently braised.
- 3 tablespoon unsalted butter divided
- 2 tablespoon olive oil divided
- 1 teaspoon fresh thyme leaves
- ½ teaspoon kosher salt plus more for seasoning and pasta water. as needed
- 4 medium onions peeled and thinly sliced
- 2 teaspoon red wine vinegar divided
- 2 tablespoon water divided
- freshly ground black pepper as need, to taste
- 2 clove garlic peeled and minced
- 1 medium radicchio quartered lengthwise
- vegetable stock as needed
- 1 teaspoon granulated sugar
- 1 pinch crushed red pepper flakes or to taste
- 1 pound dried pasta
- ¼ cup grated Parmesan cheese plus more as needed
Melt 1 tablespoon butter with 1 tablespoon oil in a large skillet set over medium heat. Once the foam subsides add onions, 1 teaspoon thyme and ½ teaspoon salt. Cook, stirring often until onions are softened somewhat, about 6 minutes. Lower heat and continue to cook slowly, stirring occasionally until well caramelized and very soft, about 50 minutes more, depending on the water content of your onions. Add 1 teaspoon vinegar and 1 tablespoon water; stirring and scraping any brown bits from bottom of the pan until most of the liquid has evaporated, about 3 minutes. Repeat with another teaspoon vinegar and another tablespoon water. The onions should be a bit jammy. Season with salt and pepper. Transfer onions to a bowl; set aside.
Bring a large pot of salted water to a boil for pasta.
Meanwhile, using the same skillet as the onions melt 1 tablespoon butter with remaining 1 tablespoon oil over medium-high heat. Add the garlic and sauté until fragrant, about 1 minute. Place the quartered radicchio pieces into the skillet cut sides down. They should sizzle. Turn the radicchio to the other cut side and add enough vegetable stock to cover them about halfway. Add remaining butter, sugar, pepper flakes & a pinch of salt. Bring the water to a boil, then lower the heat to very low. Simmer about 15 minutes until the radicchio is tender and the sauce has been reduced to a syrupy glaze. If the radicchio seems done before the glaze is achieved gently remove them to a plate using a slotted soon. Continue to cook the sauce until it has reduced to the desired consistency. Pour the sauce over the radicchio; set aside lightly covered in a warm place.
Add the pasta to the pot of boiling salted water and cook until al dente, 8 to 10 minutes. Drain the pasta, reserving about ½ cup of the cooking water. Place the pasta in the warm serving bowl. Stir in the onions, Parmesan and enough of the reserved pasta water to get the onions to coat the pasta. Top the pasta with the radicchio, either in large pieces or roughly chopped, as you prefer. Finish with a sprinkling of Parmesan and a good grinding of black pepper. Serve warm.