Kai Yaang (Whole Roasted Young Chicken)

Whisk the salt and sugar with 10 cups of tepid water in a large mixing bowl or pot until the sugar and salt fully dissolve. Combine the garlic, peppercorns, ginger, and lemongrass in a mortar and lightly pound to bruise and slightly crush them. Add them along with the cilantro and green onions to the brine, then add the birds breast side down. If they float, weigh them down with a plate. If the birds still aren't completely submerged, choose a different container. Cover and refrigerate for at least 4 hours or, even better, overnight.