It was her love for her son that drove Ms Oktaviani - who goes by one name - to cook and eat clean.
Her nine-year-old son Stan was diagnosed with autism when he was 2.5 years old. He also has epilepsy and is lactose-intolerant.
As far as possible, the 41-year-old housewife avoids using processed ingredients in her cooking and baking. She also sources for organic produce and hormone-free meats at the supermarket.
"I had to learn how to make real food - no monosodium glutamate, processed carbohydrates, sugar and gluten," says Ms Oktaviani, who was born in Indonesia.
"It is not a chore as I do it out of love for my son. I am willing to pay more for the ingredients if necessary as I want the best for him."
She moved here in 2001 and is now a Singapore citizen. Her Singaporean husband Keane Lee, 41, works in the oil and gas industry.
One healthy dessert that she makes is zucchini almond cake, a sugarless and gluten-free dessert that is also easy enough to make in a food processor.
She prefers to blanch and blend the raw almonds from scratch, rather than use store-bought ground almonds or blanched almond flour.
She says the almonds should not be blended for too long or they would become almond butter.
And instead of honey, she uses maple syrup or coconut syrup.
The resulting cake is moist and not too dense. For those who prefer a harder texture to the creamy avocado frosting, the cake can be left in the refrigerator, she adds.
She has built her knowledge over the years from books on nutrition and also consulted many nutritionists on how to cater to her son's needs.
She spends her Sundays preparing meals and shows The Sunday Times her neatly organised refrigerator, with boxes of washed fruits and cut vegetables.
And for a simple yet delicious dessert, she makes her own yogurt and chia seed pudding by mixing them with fruit, maple syrup, coconut flakes and chocolate chips.
On her Instagram page (@n3fn3f), she shares many ideas for healthy salads, overnight oats and brown rice pancakes.
She says: "People find it challenging to make 'real food' because they are not familiar with the ingredients. But once you start learning, it is much easier to substitute processed ingredients with real ones."
Ms Oktaviani, who used to run a business with her sister selling clothes and handicraft bags from Indonesia, hopes to take a nutritionist course.
"I've made a lifestyle change from just eating anything to eating clean, in the hope that I can live longer to take care of Stan," she says.
"It is not difficult to make real food if you put your heart into it."
ZUCCHINI ALMOND CAKE WITH AVOCADO FROSTING
For the cake batter
- 190g raw almonds or ground almonds or blanched almond flour
- 1/4 tsp Himalayan salt
- 1/2 tsp baking soda
- 3 eggs
- 2 Tbs coconut oil
- 4 Tbs raw honey
- 130g zucchini, grated with skin and water squeezed out
For the avocado frosting
- 2 Tbs coconut oil
- 1 ripe avocado, skin and seed removed
- 3 Tbs cacao powder or cocoa powder
- 3 Tbs raw honey
For the garnish
- Strawberries, sliced
- Preheat the oven to 180 deg C.
- Place the raw almonds in a bowl and pour hot, boiling water over them. Leave for five minutes, remove the water and rub off the skin. Then, blend the blanched almonds in a food processor on high speed for 10 seconds. Alternatively, you can buy ground almonds or blanched almond flour.
- Add the salt, baking soda, eggs, coconut oil and honey into the food processor. Blend for another 30 seconds.
- Briefly pulse in the zucchini.
- Line a 21cm by 12cm loaf pan with baking paper.
- Scoop the batter into the pan and spread it out evenly with a spatula.
- Bake for 30 minutes. When it is ready, remove from the oven and leave to cool for at least 30 minutes before adding the frosting.
- To make the frosting: In a food processor, add the coconut oil, avocado, cacao powder and honey. Blend until you get a smooth and creamy texture.
- Spread the frosting evenly onto the cake with a spatula. Garnish with strawberries and blueberries.