1) Heat a 7-litre pressure cooker over medium heat. Stir in the oil, onion, bay leaves, 22g salt, the allspice, and thyme; cook, uncovered, until soft, about 8 minutes. Increase the heat to high, stir in the tomato puree, and cook, stirring and scraping, until it turns brick red, about 2 minutes.
2) Season the chicken with some salt and black pepper, to taste, and add it to the pot, turning to coat with the tomato and onion. Stir in the water, then add the chilli, okra, potatoes, and collard greens in that order. You don't need to stir - the collards will cook down and keep everything moist as the cooker comes up to pressure. Close the pressure cooker lid and bring the pressure up to high (which can take up to 10 minutes), then reduce the heat, if necessary, to maintain an even pressure for 7 minutes.
3) Remove from the heat and press the pressure indicator stem until no more steam comes out. Carefully open the pot. Remove and discard bay leaves. Ladle the stew into bowls and serve.