In a large mixing bowl, whisk together extra virgin olive oil, vinegar, oregano, thyme, garlic, salt, and pepper.
Add prepared steak cubes to the marinade; cover and refrigerate for 2 hours, and up to 4 hours.
Once the meat has marinated, thread it onto the skewers alternating with pieces of mushrooms and red onion.
Turn on your gas grill to a medium setting and allow it to heat up for 15-20 minutes.
Using a grill brush, coat the grilling surface with oil.
When grill is ready, place kabobs on grilling surface and cook over medium heat, turning 2 or 3 times until all sides of the meat are browned and vegetables are tender, about 12 to 14 minutes.
In the meantime, prepare the mint yogurt dip. In a small serving bowl combine yogurt, garlic, lemon juice, mint, salt and pepper; whisk until well-combined.
Drizzle a little bit of olive oil over the surface of the dip.
Transfer grilled kabobs to a serving plate and serve with yogurt dipping sauce.