Combine 1 cup warm water, 1/2 cup oats, and brown sugar in a small bowl.
Dissolve yeast in 1/4 cup warm water in a bowl; let stand 5 minutes. Add oat mixture, flour, 1/2 cup oats, onion, oil, and salt; stir until well-blended. (Batter will be stiff.)
Cover and let rise in a warm place (85°), free from drafts, 45 minutes or until doubled in bulk. Stir batter well. Spoon batter into a 9 x 5-inch loaf pan coated with cooking spray. Sprinkle with 1 teaspoon oats. Cover and let rise 30 minutes or until doubled in bulk.
Preheat oven to 375°.
Uncover dough; bake at 375° for 50 minutes or until loaf sounds hollow when tapped. Remove from pan immediately; cool on a wire rack.
Bread-Machine Variation: Follow manufactrer's instructions for placing all dough ingredients in bread pan. Select cycle; start bread machine.