In a large pot, bring salted water to a boil and add the dry wheat berries. Reduce to a simmer and cook uncovered for about 1 hour, or until the wheat berries are soft yet chewy and begin to split open.

Once the wheat berries are cooked, drain them in a colander and rinse them under cold water to cool down quickly. Let them sit for a few minutes, ensuring they are well-drained.

In a large mixing bowl, add the cooled wheat berries, diced tomatoes, drained tuna, sliced green onions, and chopped parsley. Gently toss until well combined.

In a small bowl, whisk together the olive oil and fresh lemon juice until emulsified and slightly thickened.

Pour the prepared dressing over the salad mixture and gently fold until evenly coated. Season with salt and pepper to taste.

Serve immediately or transfer to an airtight container and refrigerate for up to 3-4 days.