Download a PDF of this recipe for easy reference.
Place the annatto seed, cumin seed, coriander seed, and dried oregano in a spice grinder and grind until they are a finely ground. Place the ground spices in a bowl and add the orange zest and one quarter of a cup of olive oil. Using the tip of your knife and a pinch of salt smash and grind two cloves of garlic until it is a paste and add to the bowl. Mix the contents of the bowl until a paste is formed. Spread the paste over the Cornish hen and place in a Ziploc bag to marinate. Refrigerate the marinated hen for at least 30 minutes but no more than 24 hours.
Preheat your grill. Make sure to create hot zones and cooler zones.
Grill the grape cluster, tomatillo, and red onion over a medium high temperature zone of your grill. Once they are slightly charred remove them from the grill and place them in a lidded container to steam and finish cooking. (Remove the stem of the grapes before placing in the container) At the same time grill the corn on the cob over the high heat area of the grill. Let the corn slightly char on all sides. Remove from the grill and set aside.
Remove the Cornish hen from the bag and season both sides with salt and pepper. Grill the hen bone side down on the high heat area of the grill for one minute to slightly char. Move to the medium heat zone and continue to cook for another six minutes or until the Cornish hen is mostly cooked through. Every few minutes squeeze some fresh orange juice over the hen, this will add flavor and help with caramelizing the skin. Flip and cook skin side down over the medium zone until fully cooked through (165 degrees Fahrenheit) and the skin is crispy. Remove from the grill and let rest while you finish the salsa and relish.
Place the grapes, tomatillo, and red onion mixture in a food processor along with the cilantro, garlic, lime juice, and a pinch of salt and pepper. Blitz until broken down but the salsa still has a chunky consistency.
To make the corn relish, cut the corn kernels off and place them in a bowl. Add the diced radish, Pepita, a few tablespoons of the garlic olive oil, the juice of one lime, and season with salt and pepper. Mix.
To plate, spoon a generous amount of the corn relish across the center of the plate. Lay a Cornish hen over the relish. Spoon some of the Tomatillo salsa over the hen and drizzle with some extra virgin olive oil.