*Cook's Note: Reserve the inner core of the red onion for the Black Eyed Peas and Rice recipe
For the tamarind sauce: Put the coriander seeds and cinnamon stick into a saucepan and toast over medium heat for 1 minute. Stir in the tamarind, coconut milk, grapefruit juice, water, sugar, ginger, salt, and pepper to taste, breaking up the tamarind with a spoon. Bring the ingredients to a boil, and then reduce the mixture to a simmer. Cook until the sauce has thickened, about 15 to 20 minutes. Strain the sauce into a bowl, and adjust the seasonings with salt, and black pepper, to taste.
For the marinade: Combine the shallot, ginger, garlic, oil, and black pepper in a bowl, and mix.
Add the lamb pieces to the mixture and toss to coat evenly. Cover the bowl with plastic wrap and place in the refrigerator to marinate for a minimum of 30 minutes and a maximum of 24 hours.
For the kebabs: Preheat a grill to medium-high and lightly oil the grates.
Assemble the kebabs by threading 1 piece of red onion onto a wooden skewer that has been soaked in water, followed by 1 piece of lamb through the same skewer, so the meat is resting on the red onion. Skewer the mint stems and leaves, wrapping them around the red onion and the lamb. Repeat with the remaining ingredients.
Grill the kebabs until the lamb is medium-rare, approximately 10 to 12 minutes, turning frequently.
Transfer the kebabs to a serving platter and serve with the Tamarind Sauce and the Black Eyed Peas and Rice.
Heat the vegetable oil in a saucepan over medium-high heat. Add the onion and garlic to the pan and cook until the onion is translucent. Season the mixture with salt, and pepper, to taste. Add the rice, stirring to coat the grains in the oil. Pour in the water, and stir to separate the rice. Bring the ingredients to a boil, and at this point, reduce the heat to a simmer, and place a lid over the pot. Cook the rice until tender, about 15 minutes.
Add the black eyed peas to the pot 5 minutes before the end of the cooking process.
Transfer the finished dish to a bowl, let it cool slightly, and garnish with the mint.