Grilled Polenta, Mushrooms and Peppers with Shallot Dressing

Ingredients

• 1 onion, chopped
• 2 tbsp (30 ml) olive oil
• 1 can (28 oz/796 ml) diced tomatoes
• 2 shallots, chopped
• ¼ cup (60 ml) canola oil
• 2 tbsp chopped flat-leaf parsley
• 1 tbsp (15 ml) sherry vinegar
• 1 tube (500 ml) pre-made polenta, cut into slices 1/2 inch (1 cm) thick (see note)
• 3/4 lb (340 g) portobello mushrooms, cut into slices 1/2 inch (1 cm) thick
• 3 bell peppers of various colours, seeded and cut into thick strips
• 8 green onions
• 3 tbsp (45 ml) olive oil