The pineapple needs to be removed from the sauce. Using tongs, remove the pieces to a bowl, then transfer to a cutting board. Drain the remaining drippings, the carrots and onions to a sauce pan, along with the stock and miso. Bring the mixture to a boil, whisking to combine all the ingredients and reduce until the volume is about a quart. Depending on how much pan drippings were collected, this could take about 10 – 15 minutes. Strain the liquid into a clean sauce pan, pressing on the reserved vegetables, to help them release any remaining liquid and flavor.