1 tablespoon olive oil
1 medium-size yellow onion, chopped
3 cups OR two 15.5 ounce cans navy beans or Great Northern beans, drained and rinsed
1/2 cup pure maple syrup
1 teaspoon dry mustard
1/2 teaspoon salt
1/4 teaspoon freshly ground black pepper
1/4 cup tomato paste mixed with 1 1/4 cups hot water
1. Heat the oil in a large skillet over medium heat. Add the onion, cover, and cook until softened, about 5 minutes.
2. Transfer the onion to a 3 1/2 to 4 quart slow cooker. Add the beans, maple syrup, mustard, salt, and pepper. Pour in the tomato paste mixture, cover, and cook on Low for 6 to 8 hours.