Butternut Squash, Grapefruit and Radicchio Salad with Cumin Vinaigrette

1. Preheat oven to 425ºF. Peel and cut squash into ¾ inch cubes. In a bowl, toss with 2 teaspoons of the olive oil, salt and pepper. Place squash on a parchment-lined baking sheet and roast for about 30 minutes, until tender and just starting to color. Remove from oven and let cool.
2. Cut the peel off the grapefruit and, working over a bowl, cut out supremes and place them in another bowl. Squeeze out the juice from the remains of the grapefruit. If there is any extra juice in the bowl with the supremes, pour that into the juice bowl.
3. In a small saucepan, heat the remaining 2 tablespoons of oil over medium high heat. Add the cumin and cook until very fragrant, about 2 minutes. Pour into a small bowl. Add the grapefruit juice to the saucepan, turn heat to high and reduce until thick, 5 to 10 minutes depending on how much grapefruit juice you had. Let cool and pour into bowl with oil.
4. In a large bowl, combine greens and grapefruit. Whisk together cumin mixture, vinegar and salt and pepper to taste, toss salad, and place in a wide, shallow bowl. Taste lettuce and adjust for seasoning. Gently place butternut squash pieces on top.