Romano Risotto w/ Radishes

For risotto:

• 6 cups reduced-sodium chicken broth (48 fl ounces)
• 2 cups hot water
• 3/4 stick unsalted butter, divided
• 1 medium onion, finely chopped (1 cup)
• 3 garlic cloves, finely chopped
• 1 pound Arborio rice (2 1/2 cups)
• 2/3 cup dry white wine
• 1/2 cup grated Pecorino Romano

For radishes:

• 1 tablespoon white-wine vinegar
• 1 tablespoon extra-virgin olive oil
• 1 pound trimmed radishes, julienned
• 1 tablespoon finely chopped chives

Make risotto:

1. Bring broth and water to a simmer in a 3-to 4-quart saucepan.
2. Meanwhile, heat 3 tablespoons butter in a 4-to 5-quart heavy pot over medium heat until foam subsides, then cook onion, stirring occasionally, until just softened, about 5 minutes.
3. Add garlic and cook, stirring occasionally, until softened, 6 to 8 minutes.
4. Stir in rice and cook, stirring, 1 minute.
5. Add wine and cook, stirring, until absorbed, about 1 minute.
6. Stir 1 cup simmering broth into rice and cook, stirring constantly and keeping at a strong simmer, until absorbed. Continue cooking and adding broth, about 1 cup at a time, stirring frequently and letting each addition be absorbed before adding next, until rice is just tender and creamy-looking but still al dente, 18 to 22 minutes.
7. Thin with some of remaining broth if necessary (you will have some left over).
8. Remove from heat. Stir in cheese, 1 teaspoon salt, 1/2 teaspoon pepper, and remaining 3 tablespoons butter.

Prepare radishes:

Whisk together vinegar, oil, 1/4 teaspoon salt, and 1/8 teaspoon pepper. Toss radishes with dressing and chives. Serve risotto topped with radishes.