Salsa Verde Cocida

Cut onion in half lengthwise. Set aside 1 onion half; reserve remaining onion half for another use. Heat a comal or cast-iron skillet over medium. Add ground cherries; cook, stirring occasionally, until charred in spots and starting to soften, 6 to 8 minutes. Remove from heat. 

Combine ground cherries, reserved onion half, 2 cups water, jalapeños, epazote, cilantro, garlic, and salt in a large pot. Bring to a boil over medium-high. Remove from heat. Let stand 5 minutes. Remove and discard epazote. 

Transfer ground cherry mixture to a blender. Secure lid on blender, and remove center piece to allow steam to escape. Place a clean towel over opening. Process until smooth, about 30 seconds. 

Wipe large pot clean. Add oil to pot, and heat over medium-high. Carefully add pureed ground cherry mixture. (Sauce will splatter.) Bring to a boil, and boil, stirring often, until salsa thickens slightly and you can see bottom of pot when stirring, 8 to 10 minutes. Remove from heat. Season with additional salt to taste. Serve hot or at room temperature.