Preheat the oven to 400 degrees F.
In a large oven-proof skillet or 9x13 baking dish, toss the radishes, beets, leeks and carrots, and 2 cloves of minced garlic with 2 tablespoons olive oil and 2 teaspoons sea salt. Arrange in an even layer (overlapping is fine), and drizzle 1/4 cup of wine and the lemon juice over the veggies. Braise in the oven for 1 hour, redistributing the vegetables once halfway through, until they are fork tender but still have a slight crisp bite.
Meanwhile, make the risotto: heat 2 tablespoons of olive oil in a large Dutch oven or deep saucepan. Sauté the onions over medium high heat until translucent, about 5 minutes. Add the remaining 2 cloves of minced garlic, the saffron threads and the rice. Cook for 2 minutes, until the garlic is fragrant and the rice has started to lightly toast. Pour in the remaining 1/2 cup wine and 1 teaspoon sea salt. When nearly all absorbed, add 1 cup of the stock. Bring to a simmer then turn the heat down to medium-low and cook, stirring occasionally until nearly al absorbed. Repeat this process, adding stock by ½ cup, until the rice is tender, about 25 minutes.
To serve, spoon the risotto onto plates, top with the braised vegetables, and garnish with the chives.