Blend the vinegar, garlic, oregano, 1 teaspoon of salt, and 1/2 teaspoon black pepper in a blender until the garlic is finely chopped. With the blender running, slowly blend in the oil.
Toss the baby greens, bell pepper, olives, and cheese with enough vinaigrette to coat. Season the salad, to taste, with more salt and black pepper, and serve.
