In a large pot, heat the oil over medium heat.Add the refrito blend, garlic, cumin and stir, letting it cook for about 5 minutes until fragrant. Add in the achiote or sazón and stir well (this not only enhances the flavor but also gives the sango its signature color). Cook for 2 minutes. Gradually add the plantain purée, stirring continuously to incorporate and prevent the plantain puree from clumping. Continue adding gradually until all the purée is incorporated.
Stir in the peanut butter and stir until fully combined with the puree.
Gradually add the water and continue stirring.
Season with salt and pepper to taste.
Reduce the heat to medium-low and let the sango simmer for 20 minutes, stirring every few minutes to make sure the puree doesn't stick to the bottom of the pot.
Add the shrimp and cook for another 10 minutes, until they are tender and cooked.
Stir in chopped cilantro, or leave out if you prefer. Serve the sango with a side of white rice, tostones and avocado slices. And don't forget to top each dish with a lime wedge!