Make hot and sour paste. Process ingredients in a small food processor until combined to form a smooth paste.
Place chicken in a large bowl; add hot and sour paste, 2 tablespoons of the coriander stalks and roots, and the lime rind. Mix to coat; stand for 15 minutes.
Heat half the oil in a 6.75 litre (27-cup) cast iron or other flameproof casserole dish (see tip) over high heat. Cook half the chicken, skin-side down first, for 5 minutes or until well browned all over. Transfer to a large heatproof bowl. Repeat with remaining oil and chicken; scraping base of dish to remove any caught pieces.
Wipe dish clean with paper towel. Reduce heat to low; add onion, potato, stock and any remaining marinade. Return chicken to dish; season. Cover chicken mixture with a large round of baking paper; cover dish with a tight-fitting lid. Transfer to oven; cook for 1 hour or until chicken and potatoes are cooked through. Stir in lime juice.
Serve half the chicken casserole topped with cashews and remaining coriander leaves; accompany with lime wedges (see > serve it). Transfer remaining chicken casserole to an airtight container; cool, then store (see > store it).
We used a 28cm (11¼in) round cast iron casserole dish.