Prep: Preheat oven to 375°F (190°C). Trim the tough stem from sprouts and remove outer leaves. Cut sprouts and grapes in half. Toss with oil, garlic, and salt, and spread onto a parchment paper-lined baking sheet.
Cook: Roast sprouts and grapes for 20 to 25 minutes, or until sprouts are tender and edges are golden. While they cook, whisk together balsamic and honey.
Serve: Toss cooked sprouts and grapes with balsamic mixture and feta. Serve warm.