Ingredients

• 1/2 cup coarsely chopped walnuts
• 1 tablespoon olive oil
• 1 tablespoon unsalted butter
• 1/2 medium onion, thinly sliced
• 1 1/4 teaspoons kosher salt, divided
• 1/2 teaspoon freshly ground black pepper, divided
• 1 bunch Swiss chard (about 12 ounces), stems and greens separated, stems sliced crosswise into 1/2-inch pieces, greens coarsely chopped
• 4 garlic cloves, thinly sliced
• 1/4 teaspoon red pepper flakes
• Greens from 1 bunch beets, coarsely chopped (about 1 1/2 cups greens)
• 3 teaspoons white wine or Champagne vinegar

Instructions

1. Heat a large skillet over medium and toast walnuts, shaking pan often, until fragrant, about 5 minutes. Transfer nuts to a plate.
2. Heat same skillet over medium and add oil and butter, stirring to combine. Once butter melts, add onion, 1/4 tsp. salt, and 1/4 tsp. pepper and cook, stirring occasionally, until softened and translucent, about 5 minutes. Add Swiss chard stems and cook, stirring occasionally, until softened, about 2 minutes more. Add garlic and red pepper flakes and cook, stirring constantly, until fragrant, 1 minute. Add Swiss chard greens, beet greens, vinegar, remaining 1 tsp. salt, and remaining 1/4 tsp. pepper. Cover and cook, stirring occasionally with tongs, until tender, about 3–4 minutes. Uncover and cook 1 minute more. Serve topped with toasted walnuts.