Cook the wheat berries: Bring a large pot of heavily salted water to a boil, then add the dry wheat berries. Boil for about 1 hour until they soften and split, maintaining a firm but chewy texture.

Cool the wheat berries: Once cooked, drain the wheat berries and rinse them under cold water to stop the cooking process and cool them down.

Mix salad ingredients: In a large bowl, combine the cooled wheat berries, diced tomatoes, sliced green onions, drained tuna, and chopped parsley. Stir gently to mix.

Prepare the dressing: In a small bowl, whisk together the olive oil and fresh lemon juice until they are fully emulsified and form a cohesive dressing.

Combine: Pour the dressing over the salad mixture and toss gently to ensure everything is coated evenly.

Season and serve: Taste the salad and season with salt and pepper according to your preference, then serve it fresh or store it for later!