Mung Bean Filling (For Mooncakes)

Prep time: 10 mins （plus soaking time）
Cook time: 60 mins
Yield: about 600 grams

Ingredients:
200 gm peeled split mung beans
100 gm caster sugar
80 ml coconut milk
70 ml vegetable oil
1/8 tsp salt
1½ Tbsp wheat starch

Method: 

1. Rinse mung beans. Soak over night or at least 4 hours.
2. Transfer the mung beans into a large shallow pan. Cover the mung beans with boiling water with 1cm depth. (Note: The beans will continue to absorb as much as water along the way of cooking.) Steam in a wok over medium high heat, about 25 to 30 minutes, or until it’s easily smashed with your finger tips.
3. Drain beans out and discard excess water. Use a large spoon to press through a fine sieve. You’ll get very smooth mung bean puree.
4. Transfer the puree into a non-stick frypan. Add sugar, coconut milk, oil and salt. Combine well. Cook over medium high heat until moisture is reduced by two-thirds. Sift in wheat flour in batches and stir to combine well between each addition. Reduce heat to low and simmer until thickened, stirring constantly, about 30 to 35 minutes. Transfer into a large bowl and let it cool down completely. Follow instructions of mooncake recipe to divide into portions, then shape into ball shapes. You can make mung bean filling one or two days ahead. Wrap it in plastic film and store in fridge.

Notes:

• How can you tell if the mung beans are steamed enough? If it’s easily smashed with your finger tips, it’s softened enough.
• The best mung bean filling is not too dry or not too wet. The texture should be like smooth dough, easily pulled away from pan (as shown in right bottom picture). Practice makes things perfect. You’ll get the hang of things after one or two trials.

Source here