Segment the grapefruits, reserving 2 tablespoon of the grapefruit juice. Drink or save remaining juice. Place segments in a large salad bowl. Pit and slice the avocado. Remove slices from avocado skin and place in the same bowl as the grapefruit. Add the greens, mint, strawberries, and cheese to the bowl.
Combine the reserved 2 tablespoon of grapefruit juice, vinegar, and olive oil in a small bowl or jar with tight fitting lid. Whisk or shake to emulsify. Drizzle about half the dressing onto the salad and toss to combine. Taste, and add more dressing if necessary. Season with salt and pepper. Toss to combine again.Serve and enjoy!