Marinate meat: Mix garlic, 1 tbsp. ginger, and the soy sauce in a bowl. Add riblets to bowl, tossing to coat. Chill at least 1 hour and up to overnight, stirring occasionally.
Make glaze: Combine preserves, hoisin, vinegar, jalapeño, and remaining 1 tsp. ginger in a small saucepan. Cook over medium heat, stirring often, until bubbling. Remove from heat and set aside.
Cook ribs: Prepare a grill for medium indirect heat (350° to 450°; for gas, turn off heat under 1 burner; for charcoal, heap charcoal on 1 side of firegrate). Grill ribs over direct heat portion of grill, covered, turning once, 15 minutes or until browned.
Reduce heat to very low (200° to 250°; for charcoal, partially close air vents to lower heat, and check temperature with an oven thermometer set on indirect heat area). Move ribs to indirect heat area and cook, covered, until tender and meat is starting to pull away from edge of bone, about 30 minutes.
Brush ribs generously with glaze and cook, covered, turning once, until glaze is bubbling, about 8 minutes total.
Toss riblets in a large bowl with peaches and remaining glaze. Transfer to a platter and sprinkle with green onions.
*Ask a butcher to cut a rack of ribs in half lengthwise, then slice between each rib to make 26 to 32 bite-size riblets.
Note: Nutritional analysis is per serving.