http://blog.womenshealthmag.com/

Ingredients
1 pint quartered cherry tomatoes
1 Tbsp red wine vinegar or balsamic vinegar
2 large bunches Swiss chard or rainbow chard
1 large chopped yellow onion
3 Tbsp extra-virgin olive oil
4 cloves garlic, minced
1/2 tsp sea salt
1/2 tsp freshly ground black pepper

Directions
In a small bowl, toss cherry tomatoes with vinegar. Set aside. Remove chard leaves from stems. Chop leaves, place in a large bowl of cool water, and swirl to rinse. Transfer to a colander, allowing a bit of water to remain on leaves. Rinse, dry, and thinly slice stems. In a large skillet over medium heat, saute chard stems and onion in olive oil until softened, about 10 minutes. Reduce heat to low. Add garlic and saute 1 minute. Add chard leaves, salt, and pepper. Turn heat to high and toss with tongs until leaves wilt. Add cherry tomatoes and vinegar to skillet, then serve.