Black turtle beans are widely used in Latin American dishes, from Brazil's feijoada to the simple bean soups of Cuba and Mexico. We've taken the latter approach, simply adding cumin and oregano to the soup base. A good pinch of dried epazote, a Mexican herb, would add another savoury note; it's available online from good Mexican shops such as Monterey Foods and Fireworks Foods. Finish the soup with a good scattering of feta, which is similar to queso fresco, the fresh cheese used in Latin American cooking, and a few slices of ripe but firm avocado.
Dried black turtle beans are available online from Monterey Foods (montereyfoods.com.au).