In a large bowl, toss venison, flour, salt and pepper, and coat evenly. Heat 3 tablespoons oil in a large pot over medium-high heat. Add venison, and brown evenly. Remove venison from pot, and set aside.
To the same pot, add wine and stir to deglaze pot. Add 2 more tablespoons oil and onion, carrots, bell pepper and garlic. Cook, while stirring occasionally, for 5 minutes. Return meat to the pot, add stock and bay leaf, and bring to a boil. Reduce heat to low and simmer, uncovered, for 45 to 60 minutes or until meat just starts to get tender.
Add tomato paste, sweet potatoes, thyme and sugar. Simmer for another 15 to 20 minutes. When sweet potatoes are just cooked, season to taste with salt and pepper.
To serve, spoon couscous into bowls, and ladle stew over. Sprinkle parsley on top.