Place quinoa in a fine sieve; place sieve in a large bowl. Cover quinoa with water. Using your hands, rub grains together for 30 seconds; rinse and drain. Repeat procedure twice. Drain well.
Combine 6 cups water, salt, thyme, and bay leaf in a large saucepan; bring to a simmer over medium heat. Cover and cook 5 minutes; discard thyme and bay leaf. Keep warm over low heat.
Melt butter in a medium sauté pan over medium heat. Add onion, and cook for 10 minutes, stirring frequently. Add quinoa; cook 2 minutes, stirring constantly. Add warm seasoned water, 1/2 cup at a time, stirring frequently until each portion of warm seasoned water is absorbed before adding the next (about 30 minutes total). Stir in vinegar. Spoon 2/3 cup risotto into each of 6 small bowls or plates; top each serving with 1 1/2 teaspoons crème fraîche. Sprinkle each serving with 1 1/2 teaspoons hazelnuts.