Preheat the oven to 400 degrees Fahrenheit.

Arrange the fennel, carrots, parsnips and garlic in a single layer on a cookie sheet lined with parchment paper. Drizzle with the olive oil, vinegar and maple syrup. Sprinkle with salt and pepper to taste. Tuck the thyme into the vegetables.

Roast, uncovered, in the center of the preheated oven, stirring for about 45 minutes or until the edges begin to brown. Stir once to redistribute.