Remove the skin of the plantain and cut into 1/2-inch roundels. In a non-reactive mixing bowl combine the plantains, tamarind pulp, salt, and turmeric and let it rest for 5 minutes at room temperature.
In a medium skillet heat the oil on medium heat. Add the coriander seeds, ginger, garlic, asafetida and cook, stirring continuously until fragrant and garlic turns golden brown, about 2 to 3 minutes.
Add the plantain mixture to the skillet with 1 cup water. Stir well to combine all the ingredients and bring it to a boil. Reduce the heat to low and simmer until plantains are cooked through. Add a little more water if required.
Stir in the mint leaves and cook for another minute and serve hot.
In a large saucepan, cook the yams for 8 to 10 minutes in salted boiling water just until tender. Drain and keep it warm.
In the saucepan heat the oil on medium heat and fry the mustard seeds and garlic, stirring continuously until very fragrant, about 2 minutes. Add the yams, lemon juice and season it with salt, stir until well combined.
Serve it warm on a bed of upland cress.