Add the green beans and halved potatoes to a large bowl. Drizzle with olive oil, then add the garlic, thyme, rosemary, salt, and pepper. Toss until evenly coated.
Spread the vegetables in a single layer on a baking sheet.
Roast for 30–35 minutes, stirring halfway through, until the potatoes are tender and golden and the green beans are lightly crisp.
Serve warm.
Notes
Spread the vegetables out on the pan so they roast instead of steam.
Line the baking sheet with parchment paper for easier cleanup and less sticking.
Add fresh rosemary or thyme after roasting for extra flavor if you have it on hand.
Finish with a squeeze of lemon juice before serving for a little brightness.
Add smoked sausage or grilled chicken to turn this side dish into a full meal.