Adobong Baboy (Filipino Pork Adobo)

Whisk tamari (or soy sauce), vinegar and sugar in a small bowl until the sugar is dissolved. Set aside.

Rinse spareribs under cold water and pat dry. Using a butter knife, remove the silver skin membrane from the underside of the ribs by sliding the knife between the membrane and the bone. Slice the meat between the bones into individual ribs.

Heat oil in a large skillet or Dutch oven over medium-high heat. Working in 2 batches, cook half the ribs, flipping once, until browned, 3 to 5 minutes per side. (Adjust the heat to prevent the bottom of the pan from burning.) Transfer to a plate. Repeat with the remaining ribs.

Add onion (or shallot), garlic and peppercorns to the pan; cook, stirring occasionally, until browned, about 3 minutes. Return the ribs to the pan along with the tamari mixture. Bring to a boil. Reduce the heat to a low simmer, cover and cook, turning the ribs once, until the meat is tender and falling off the bone, about 2 hours. 

Using tongs, transfer the ribs to a serving platter. Strain the sauce through a fine-mesh strainer into a medium bowl (discard solids). Carefully skim off and discard the fat. Pour the sauce over the ribs and sprinkle with scallion and fried garlic, if desired.