Heat a griddle skillet to medium heat and coat with a little olive oil. Slice peaches then lightly press them into the skillet to get grill makes. Cook each side for 2-3 minutes then rotate until nice grill marks form.
In a small bowl, whisk together 1 tablespoon olive oil, 1/2 teaspoon red wine vinegar, 1 teaspoon lemon juice, 4 teaspoons balsamic vinegar, pinch of sugar and a pinch of salt. Add a dash of pepper, if desired.
In a large bowl, toss mixed salad greens, strawberries and grilled peaches with dressing.