Brush the salmon fillet lightly with olive oil. Season evenly with salt and pepper. Set aside.
Prepare a grill fire to 300°.
Make the glaze: In a small saucepan, whisk together the orange marmalade, juice, soy sauce, apple cider vinegar, honey, granulated garlic, corn starch, salt, and pepper. Cook over medium heat, stirring often, until the glaze thickens.Remove from heat and set aside.
Place the salmon on the grill skin side down. Cook slowly until the internal temperature reaches 100° using a digital meat thermometer.
Transfer the salmon to a large piece of foil. Spoon a thick layer of orange glaze over the top. Cover with a second piece of foil and seal to form a foil packet.
Return the foil packet to the grill. Continue cooking until the salmon reaches 135° using a digital thermometer.
Remove from the grill and let rest for 5 minutes. Carefully open the foil and transfer the salmon to a serving platter.
Serve with additional orange glaze if desired.