> Cooking spray
> 1 medium zucchini
> 1 tbsp olive oil
> 1 (10 oz) container mirepoix (chopped carrots, onions, and celery)
> 1 green bell pepper, seeded and finely chopped
> 1 lb 93% lean ground beef
> 1 cup quick-cooking oats
> 1 large egg
> 1 tbsp Worcestershire sauce
> 4 tbsp ketchup, divided
> 1 tbsp yellow mustard
Preheat oven to 400°F. Coat a 9x5-inch loaf pan with the cooking spray. Using a box grater, coarsely grate the zucchini. In a 12-inch skillet, heat the oil on medium-high. Add the mirepoix and bell pepper and cook 5 min. Add zucchini and cook 2–3 min. more, until all vegetables are tender. Season with salt and pepper. Transfer vegetables to a large bowl and let cool slightly.
To bowl with vegetables, add the ground beef, oats, egg, Worcestershire sauce, and 3 tbsp ketchup. Season with salt and pepper. Mix gently but thoroughly. Transfer meat mixture to prepared loaf pan. Season with salt and pepper.
In a small bowl, combine remaining 1 tbsp ketchup and mustard. Press meat mixture into loaf pan, then smooth top. Brush top with ketchup mixture. Bake 45–50 min., until internal temperature reaches 160°F. Let rest 5 min.