Place dough in large bowl. Cover with towel and let rise in warm draft-free area until doubled, about 1 hour.
Preheat oven to 450°. Heat 2 tablespoons oil in large nonstick skillet over medium heat. Add onions and garlic and saute until brown and tender, about 10 minutes. Add mustard, mustard seeds and thyme and stir 1 minute. Cool.
Oil large baking sheet. Using rolling pin, roll out dough on floured surface to 14×5-inch rectangle. Spread 1/3 cup onion mixture evenly over dough. Starting at one short end, roll up dough jelly roll style. Using rolling pin, roll out dough to 12×8-inch rectangle. Transfer to prepared baking sheet. Brush with remaining 1 tablespoon oil. Sprinkle remaining onion mixture atop dough.
Bake bread until golden brown,
about 20 minutes. Serve warm or at room temperature.
Thanks to purchased frozen dough, this bread is a snap to make. Serve it with soups, salads and pastas.