Heat a skillet or grill pan to medium high heat. Spray with cooking spray.
Season both sides of steak with salt & pepper. Cook about 4 minutes per side for medium-rare. Remove the steak from the skillet and add the tomatoes. Stir occasionally and cook 2-3 minutes.
Add garlic, vinegar and oregano. Stir to combine and cook another two minutes. Remove from pan.
To the serving plates add a layer of arugula. Divide steaks amongst the plates and then the tomatoes. Drizzle extra balsamic vinegar over the plate and serve.
**For the grill. Add steaks to the grill. Meanwhile make a foil pack with tomato, garlic, vinegar and oregano mixture. Grill the foil pack alongside the steaks for about 8 minutes.