Step 1

Preheat the oven to 350°F and set an oven rack in the middle position. Line a rimmed baking sheet with heavy-duty aluminum foil. Place the walnuts on the prepared baking sheet and bake until until fragrant, 5 to 10 minutes. Keep a close eye on the nuts so they don't burn. When cool enough to handle, transfer the nuts to a cutting board and coarsely chop. Place the foil back on the baking sheet (you'll use it for the green beans) and increase the oven temperature to 450°F.

Step 2

Place the cranberries in a small heatproof bowl. Cover the cranberries with boiling water and set aside.

Step 3

Directly on the foil-lined baking sheet, use a rubber spatula to toss the green beans with the olive oil, garlic, salt, pepper, and sugar. Roast the green beans for 15 minutes, then stir with a spatula to promote even cooking. Continue roasting until the beans are tender, slightly browned and just starting to shrivel, about 10 minutes more.

Step 4

Drain the cranberries.

Step 5

Add the lemon zest, lemon juice, drained cranberries, and toasted walnuts to the green beans. Toss well, then taste and adjust seasoning if necessary.