Mix garlic, peppercorns, sugar, fish sauce, and lime juice in a bowl.
Marinate chicken pieces in the fridge for at least 2 hours or overnight.
Thread marinated chicken onto parallel pairs of soaked bamboo skewers.
Preheat the grill to high or prepare a barbecue.
Grill chicken for 6-7 minutes until golden-brown and cooked through.
Cut barbecued chicken into chunks and set aside.
Blend spice paste ingredients in a food processor until smooth.
Cook rice in boiling salted water for 12-15 minutes until tender.
Drain and rinse rice with boiling water, then spread on a tray to cool.
Shallow fry sliced shallots in 1cm of oil until crisp and brown.
Drain fried shallots on kitchen paper and season with salt.
Beat eggs with salt and pepper and fry in three batches to make thin omelettes.
Roll up the omelettes and slice into thin strips.
Heat a wok, add two tablespoons of oil, and stir-fry spice paste for 1-2 minutes.
Mix in tomato purée and ketjap manis, then stir-fry the cold rice.
Toss in chicken, shallots, and omelette strips for one minute.
Mix in soy sauce, cucumber, and most of the spring onions.
Serve on a platter garnished with remaining spring onions.