Combine all of the salsa ingredients and set aside until needed.
Set the EGG for direct cooking (without the convEGGtor) at 350°F/177°C.
Slice off the top of the tomatoes and scoop out the seeds and insides, being careful not to break the skin. Set upside-down on a paper towel to allow juices to run out for 10 minutes.
In a Stir Fry & Paella Pan, caramelize the onions. Brown the lamb with the salt and pepper. Add the mushrooms and 3 tablespoons of the tomato and cook for 1 minute. Add most of the feta cheese, reserving some for topping. Cook for 1 minute and remove from heat.
Place tomatoes on Grill Rings; fill tomatoes generously. Grill for 5-6 minutes or until tomato skins crack open slightly. Remove from heat, top with cucumber salsa and enjoy!