Engagement Roast Chicken

INGREDIENTS

• 1/2 cup chicken stock, preferably homemade
• 1 tablespoon all-purpose flour
• Good olive oil
• 1 whole head garlic, cut in 1/2 crosswise
• Kosher salt and freshly ground black pepper
• 1 (4 to 5 pound) roasting chicken
• 2 lemons
• 2 Spanish onions, peeled and thickly sliced
• 1/2 cup dry white wine