Heat oil in a large, heavy-based saucepan over medium-low heat.
Cook onions, stirring occasionally, for 20 minutes or until softened. Add bay leaf, thyme, sugar, vinegar and wine.
Cook, stirring occasionally, for 10 minutes or until onions is browned and caramelized.
Add garlic to onion mixture.
Cook, stirring, for 2 minutes or until fragrant. Add stock, barley and 2 1/2 cups cold water.
Bring to the boil.
Reduce heat to low. Simmer, stirring occasionally, for 30 minutes or until slightly thickened and reduced. Season with pepper. Remove and discard bay leaf and thyme.
Make croutons Preheat grill on medium-high heat. Line a baking tray with foil. Combine cheeses in a bowl. Season with pepper. Using an 8cm round cutter, cut 4 rounds from bread. Place rounds on prepared tray.
Grill for 1 to 2 minutes or until light golden. Remove from grill. Turn bread over. Top with cheese mixture. Grill for 1 to 2 minutes or until cheese is browned and melted.