For the crushed wheat: Soak the crushed wheat in cold water for 30 minutes, until the grains swell. Drain and transfer to a medium saucepan. Cover with water, add salt, and bring to a boil. Cook until tender, 20 minutes. Drain under cold running water.
For the tuna: In a bowl, mix together the garlic, lemon zest, lemon juice, cilantro, parsley, olive oil, cayenne and some salt and pepper. Rub on the tuna with a fork.
Heat a grill pan over medium-high heat and oil the pan. Sear the tuna until browned on the outside but still pink in the middle, about 2 minutes per side.
For the dressing: In a jar, combine the olive oil, lemon juice, soy sauce, honey and some salt and pepper. Shake well.
For the salad: In a large bowl, combine the cooked crushed wheat, cherry tomatoes, parsley, spring onions and cucumbers. Toss well. Add some of the dressing and toss again.
To serve: Tip the salad onto a large serving platter. Slice the tuna, maintaining its shape; set on top of the salad. Garnish with parsley leaves.
Cook's Note: If fresh tuna is unavailable, feel free to substitute two 6-ounce cans tuna in brine, drained.