Add quinoa to 2 cups boiling water and cover for 12-15 minutes or until the germ separates from the seed. The cooked germ looks like a tiny curl. Remove it from heat and let it stand for about 3 minutes to become fully fluffy. Let cool.
Add lemon juice, parsley, mint, scallions, and plum tomato to the quinoa and toss to combine. Dress the salad with 2 tablespoons extra-virgin olive oil. Salt and pepper, to your taste.
Cut off tops of tomato. Scoop out some of the inside of tomato. Season the tomatoes with salt and pepper and cover with a generous amount olive oil. Place on the grill for 3 minutes turn and grill for 3 more minutes. Remove from grill.
To serve, pile a generous amount of tabbouleh salad on top of the tomato, allowing the salad to spill down and over tomato on to the plate.