Heat the olive oil in a large saucepan over medium heat. Sauté onion for 5 minutes, or until softened. Add garlic and spices, and cook, stirring, for 1 minute, or until fragrant.
Add the tomatoes; simmer for 3–4 minutes. Add chopped sweet potato and beans with 1 cup of water, and bring to the boil. Partially cover and simmer for 20 minutes, or until potato is tender and mixture is thick.
Meanwhile, divide the baby spinach and sliced cucumber between serving bowls. Top with the bean mixture, sliced avocado and crumbled feta.