2 teaspoons olive oil, optional
1 medium-size yellow onion, minced
3 garlic cloves, minced
2 teaspoons grated fresh ginger, optional
1 teaspoon ground coriander
1 teaspoon ground cumin
1 teaspoon curry powder
¼ teaspoon cayenne pepper
2 medium-size sweet potatoes, peeled and cut into ½-inch dice
1 green bell pepper, seeded and cut into ½-inch dice
3 cups cooked kidney beans or 2, 15-ounce cans beans, rinsed and drained
1 14.5-ounce can diced tomatoes, with their juices
⅓ cups peanut butter, preferably crunchy
1½ cups vegetable broth
Salt and freshly ground black pepper
6 cups coarsely chopped fresh spinach or Swiss chard
For the best flavor, heat the oil in a medium-size skillet over medium-high heat. Add the onion and sauté until softened, about 5 minutes. Add the garlic and cook for 1 minute longer, then stir in the ginger (if using), coriander, cumin, curry powder, and cayenne. Alternatively, omit the oil and sauté these ingredients in a few tablespoons of water or combine them in a microwave-safe bowl with a little water, cover, and microwave for 2 minutes.
Transfer the onion mixture to the slow cooker. Stir in the sweet potatoes, bell pepper, beans, and tomatoes and their juices.
Ladle about ½ cup of the broth into a small bowl and whisk in the peanut butter, then scrape the mixture into the slow cooker along with the remaining broth. Season to taste with salt and pepper. Cover and cook on low for 5 hours.
Stir in the chopped spinach, then cover and continue cooking for 1 hour. Alternatively, place the spinach in a microwave-safe bowl, cover, and microwave until wilted, 2 to 3 minutes, then add the spinach to the stew just before serving time.