1 TBSP olive oil
1 medium onion, peeled and cut into half rings
1 large bunch fresh Kale (or other tough greens)
2 10 oz cans diced tomatoes with green chilies
2 TBSP balsamic vinegar
salt and pepper to taste
Wash the greens thoroughly and cut into a fairly fine chiffonade. Set aside. In a heavy pan (preferably non stick) with a good lid, heat the oil and add onions. Cook, stirring, until translucent and starting to brown. Add green a few at a time and continue stirring and adding as the greens cook down. They will cook down a lot. Add the undrained tomatoes and stir in. Reduce heat to a simmer and cover and cook about 30 minutes. Add vinegar and salt and pepper and serve.