In a food processor, pulse the flour, butter and salt until the butter is the size of small peas. Pour in the milk and pulse again until the dough just begins to hold together, adding more milk if needed. Remove the dough from the food processor and shape into a square with your hands.
On a floured work surface, roll the dough into a 16x6inch (40x15 cm) rectangle. Line a 14x4inch (35x10 cm) rectangular tart pan with removable bottom with the dough and trim the edges. Place in the freezer for 15 minutes or the refrigerator for 30 minutes.
With the rack in the middle position, preheat the oven to 400°F (200°C).
Bake the cold crust for 15 minutes or until lightly browned.
In a skillet over medium heat, soften the onion and garlic in the oil. Add the bell pepper and zucchini. Cook for about 5 minutes or until the vegetables are tender. Add the tomatoes and cook until the vegetables are soft and the liquid has evaporated. Season with salt and pepper.
Spread the ratatouille into the crust. Top with the cheese and bake for about 10 minutes or until the cheese has melted.
In a bowl, toss the arugula with the olive oil and vinegar. Place the arugula salad on the tart. Serve as an appetizer or with fried eggs for brunch.
The ratatouille can easily be doubled and saved for another meal.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.