Venetian Radicchio Risotto

From the garden

• 2 heads radicchio heads (Treviso or Chioggia), quartered, cored, and finely shredded
• 1 small yellow onion, finely diced

From the pantry

• 4 tbsp butter · divided; half goes in at the end
• 1 tbsp olive oil
• 1½ cups arborio or carnaroli rice
• ½ cup dry white wine
• 6 cups vegetable stock, kept warm in a saucepan
• ¾ cup parmesan, finely grated
• 2 tsp balsamic vinegar · added drop by drop at the finish
• salt · to taste
• black pepper

1. Quarter the heads, cut out the solid white core, and shred the leaves as finely as slaw. Set a loose handful aside raw for the top, where it keeps a bitter crunch against the soft grains.
2. Melt 2 tablespoons of the butter with the olive oil in a wide heavy pot over medium heat and cook the onion with a pinch of salt 4–5 minutes, until translucent. Add the shredded radicchio and stir 5 minutes, until it collapses and darkens to a deep brick color.
3. Add the rice and toast, stirring, 1–2 minutes until the edges of the grains turn translucent, then pour in the wine and stir until it has cooked away entirely.
4. Ladle in the warm stock a little at a time, stirring often and adding more only once the last addition is mostly absorbed. After 18–22 minutes the rice should be al dente and the risotto should spread slowly when a spoonful is tipped onto a plate.
5. Beat in the remaining butter and the parmesan off the heat, then the balsamic a few drops at a time, tasting as it goes, because the vinegar and the salt together are what turn the bitterness sweet. Scatter the reserved raw radicchio over, grind on pepper, and serve at once.