Make the Mango Pico de Gallo: Mix together the mango, onion, jalapeno, lime juice, oil, honey, and recao or cilantro in a medium bowl. Season with salt and pepper, to taste, and stir to combine. Let sit at room temperature for 30 minutes before using.
Mix together the horseradish and ancho chili powder in a small bowl. Season with salt, to taste.
Heat grill to high. Dip oysters in water, as this will help them steam open on the grill. Place oysters on the grill, close the cover, and grill until all have opened, about 3 to 4 minutes. Discard any that do not open. Place a tablespoon of the Mango Pico de Gallo on top of each oyster and top that with a scant teaspoon of the Red Chili Horseradish.