Mix turmeric, cumin, and water into a paste then rub over the chicken and chill overnight.
Pulse peanuts in a processor and blend lemongrass, galangal, and garlic into a fine paste.
Combine the paste with coconut milk, ketjap manis, chilli flakes, lime zest, and peanuts, then chill overnight.
Preheat the oven to 120°C.
Place chicken in a tray, cover with marinade, and roast for two hours while basting occasionally.
Increase oven temperature to 200°C and roast for another 20 minutes.
Remove chicken from the oven, baste again, and let it rest for 20 minutes.
Blend peppers, chillies, garlic, sugar, and vinegar into a rough purée for the dip.
Boil the purée for three minutes, whisk in cornflour until thick, and add lime juice, salt, and chilli flakes.
Combine spring onions, peanuts, green chillies, cucumber, and coriander in a bowl for the salad.
Whisk honey, soy sauce, sesame oil, and lime juice together and toss with the salad.
Serve the roasted chicken with the chilli dip and salad.