1/2 cup raisins
2 tablespoons sherry vinegar
2 bunches Swiss chard, preferably rainbow, stems removed, leaves sliced
1 red onion, sliced
1/4 teaspoon sea salt
1/4 cup walnuts, toasted and chopped
Put raisins and vinegar in a small bowl with 1/4 cup boiling water. Set aside to let soak 10 minutes.
Heat a large pot over medium-high heat. Drain and reserve raisins; add liquid to the pot. Add chard a few handfuls at a time, stirring and letting the chard cook down until all of it fits in the pot. Add onion and salt, lower heat to medium, cover and cook until onion and chard are tender, 10 to 12 minutes. Stir in raisins and cook 1 minute longer. Top with walnuts and serve.