Add 1 tablespoon sesame oil to the 1 1/2 tablespoon duck fat. Turn on the stove to medium heat.
Add the onions, celery, carrots, ginger, garlic, thyme, scallions, reserving some for garnish. Season with a pinch of salt and pepper. Stir and cook 2 to 3 minutes until fragrant .
Add in the tomatoes. Stir or mix. Cook 2 to 3 minutes until the tomatoes starts to break down.
Add in the anise, cinnamon stick, bay leaves and potatoes. Season with the remaining salt and pepper. Stir.
Add in the lime juice, rice wine vinegar and soy sauce. Stir and cook until liquid is reduced to half. About 1 to 2 minutes.
Pour in the water - 4 to 5 cups.
Stir. Bring to a boil.