Cook ground beef and chopped yellow onion in a skillet over medium heat until beef is no longer pink, about 5-7 minutes.
Add green beans, chopped zucchini, tomatoes, mushrooms, dried oregano, salt, and pepper; stir well and continue cooking for about 10 minutes until vegetables are tender.
Remove skillet from heat and serve hot.
Notes
This one-pan dish is perfect for a quick and healthy weeknight dinner, packed with protein and fresh vegetables.