Cut the onion and chicken into medium-sized chunks and place them in two separate bowls.
Drain the juice from the can of peaches into a measuring cup. I do this by only opening the lid a small amount; enough to drain the liquid, but not so much that pieces of peach can fall out.
Add approximately as much water to the measuring cup as there is peach juice. I get approximately 175ml (3/4 cup) of juice from a 425g (15oz) can of peaches. If your peaches have less juice, you may need to add more water, to make sure there's enough liquid to cover the chicken.
Heat the oil in the pan over medium-high heat.
Cook the onion until they're soft and translucent, approximately 3 minutes
Once the onion is translucent, add the chicken, and season with salt and pepper. Stir and cook until the outside of the chicken is fully cooked, but the inside doesn't have to be fully cooked. Approximately 7 minutes
Add the water with peach juice, tomato paste, sambal, and ketjap manis, and stir until fully combined.
Let simmer for 30 minutes
Cut the peaches into small pieces (same size as the chicken), and add. Let warm through for approximately 5 minutes before serving.
