Begin by heating olive oil in a pan. Once hot, add the washed and drained lamb liver, sautéing until it changes color, which should take about 10 minutes. During this time, stir occasionally. Next, introduce the sliced onions to the pan, continuing to sauté until they wilt. Following this, pour in the dry red wine, stirring well to help evaporate the alcohol. Now, incorporate the flour into the mixture. Prepare the chicken stock by dissolving a cube in two cups of water, and then add this to the liver. Allow this to boil for about 5 minutes. It's then time to add the bay leaf, rosemary, and thyme. Add the remaining cup of water and let the mixture simmer over low to medium heat. This should be done until the sauce thickens and the liver is fully cooked, which generally takes around an hour. Once this consistency is reached, stir in the pomegranate syrup, salt, and pepper, cooking just a bit longer until the liver is well-coated with its own oil. After removing from the heat, let the mixture cool down. Then, transfer the liver mixture into a tart pan. Cover the mixture with a sheet of thawed puff pastry, pressing it lightly to remove any excess air. Trim the pastry around the edges, leaving about 2 cm of overhang, and tuck these edges inward, pressing against the pan to seal. The pastry should then be brushed with a beaten egg. With any leftover pastry, create four strips and place them in the center of the tart. Cut a cross in the middle of the pastry with a knife. Finally, bake in a preheated oven at 200°C (392°F) for 20-25 minutes, or until the pastry turns a golden brown. Garnish with fresh thyme before serving