In a bowl, combine all the ingredients. Season with salt and pepper. Shape into 8 meatballs, using about 1/3 cup (75 ml) of the mixture for each. Set aside.
In a large non-stick skillet over medium heat, soften the onion and garlic in the oil. Add the tomatoes and bring to a boil. Season with salt and pepper. Let simmer for 5 minutes. Add the meatballs and cover. Let simmer for 10 minutes, turning the meatballs halfway through cooking. Adjust the seasoning.
In a large skillet over high heat, sauté the spinach in the oil until wilted. Season with salt and pepper. Drain in a sieve. Set aside.
On a grill pan or in a hot oven, toast the buns. Divide the wilted spinach on the bottom buns and add the meatballs. Drizzle with the tomato sauce. Cover with the top buns.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.