1) Heat olive oil in a medium pot over medium-high heat. Add onions and salt and saute, until onion becomes translucent and tender, about 5 minutes. Add rice and saute another 2 minutes to toast rice. Add coconut milk and fill saucepan with enough water to cover the rice by 1cm or measure by placing your thumb tip on the rice and filling the pot with water until the water reaches the middle of your thumbnail.
2) Bring rice to a simmer, cover and cook until rice is tender and liquid has evaporated, about 15 to 17 minutes.
3) Remove from heat and let rice stand another 5 minutes, covered.
4) Fluff rice with fork and then fold in pigeon peas. Season with salt and pepper, to taste.
5) Serve immediately.