Season the turkey breast with a pinch of salt, black pepper, and dried oregano.
Preheat a grill or grill pan over medium-high heat and lightly coat with a touch of oil.
Grill the turkey breast for 5-7 minutes per side or until the internal temperature reaches 165°F.
While the turkey rests, whisk together the olive oil, lemon juice, and Dijon mustard in a small bowl to create the dressing.
Rinse and drain the cannellini beans thoroughly.
In a large bowl, combine the mixed greens, white beans, cucumber, and cherry tomatoes.
Drizzle the dressing over the salad and toss gently to coat.
Slice the grilled turkey breast into strips and the avocado into thin wedges.
Top the salad with the turkey and avocado, and serve immediately.