If you don't overcook brussel sprouts then they do develop a slightly sweet taste after cooking so seasoning them with an ingredient that plays up that sweetness makes sense.
Roasted Brussel Sprouts with Balsamic Vinegar
Rinse the brussel sprouts; cut off the stem and cut in half.
Line a baking sheet with aluminum foil. In a large bowl, toss brussel sprouts with 2 tablespoons Garlic Olive Oil, salt and pepper.
Transfer the brussel sprouts to baking sheet ( lined with foil) and roast, stirring occasionally to ensure even browning, until tender and caramelized, about 20 minutes.
Place the Fig Balsamic Vinegar in a small saucepan and cook on low heat, stirring regularly. Reduce the vinegar until it begins to coat your spoon and decreases in volume. (About 10 minutes) Remove from heat and set aside.
Add the brussel sprouts back into the original bowl. Add remaining tablespoon of Garlic Olive Oil, the Fig Balsamic reduction and toss to coat evenly.
Taste and adjust seasoning if necessary, then serve.