Salad Barat Daya Pedas dengan Saus Alpukat

Bahan-bahan (4 porsi)

• 2 sweet potatoes
• 1 tablespoon oil
• 1 heaping teaspoon each cumin and chili powder (plus a sprinkle of cayenne if you like it hot)
• salt and pepper to taste
• 1 14 -ounce can black beans, rinsed and drained
• 1 14 -ounce can sweet corn, rinsed and drained
• 1 romaine heart, chopped
• half an avocado
• 1/4 cup Greek yogurt
• 1/2 cup water
• 1 cup cilantro leaves and stems
• 1 small clove of garlic
• 1/2 teaspoon salt
• a squeeze of lime juice