Layout tortilla flat and add cheese to just 1/2 of it. On top of cheese add tomatoes, cilantro, grilled chicken and green onions.
Fold other half of tortilla over cheese half and brush a little vegetable oil on both sides.
Add to preheated Foreman Grill (use medium setting) and close lid. Check after 2 minutes for doneness. Quesadillas will be ready in 2-5 minutes.