In a large saucepan, combine chicken, water, celery, bay leaf, onion and garlic. Season with salt and pepper. Cook until chicken is tender. Strain, reserving the stock. Remove skin and bones from the chicken; set the meat aside.
Toast the sesame seeds lightly in a frying pan, stirring constantly, until they are fragrant. (Watch them, the can burn quickly.) In a food processor or blender, puree the sesame seeds and almonds with a cup of the reserved chicken stock.
Heat oil in a frying pan over medium low heat. Add the sesame seed and almond mixture, and cook for 5 to 8 minutes, or until thickened. Stir in another cup of the reserved chicken stock and bring to the boil. Add chicken stock cube and reduce heat to simmer for 5 minutes. Stir in the diced chillies, olives, capers and chicken. Simmer for 10 minutes. Serve hot.
Guero chillies are small and yellow, giving medium heat. They also go by the simpler term "yellow hot chilli". If you're unable to find this variety, use a milder green chilli.