The first step in making Doubanjiang is to soak the beans. Rinse the dried broad beans and soybeans in cold water, then place them in a large bowl and cover them with water. Let the beans soak for at least 12 hours, or overnight.

After soaking, drain the beans and transfer them to a large pot. Cover the beans with water and bring the pot to a boil. Reduce the heat to low and let the beans simmer for 2-3 hours, or until they are tender and easily mashed with a fork.

While the beans are cooking, you can prepare the chili paste. Combine the chili flakes, salt, sugar, rice wine, and water in a bowl and stir until well combined.

Once the beans are cooked, drain them and let them cool for a few minutes. Then transfer the beans to a food processor or blender and pulse until they are coarsely mashed.

Add the chili paste to the mashed beans and continue to blend until the mixture is smooth and well combined.

Transfer the blended mixture to a large glass jar or crock. Cover the jar with cheesecloth or a clean kitchen towel and let it sit at room temperature for 2-3 days.

During this time, the mixture will ferment and develop its complex flavors. You may notice some bubbling or a slight sour smell, which is normal.

After 2-3 days, stir the mixture and taste it. If it's not spicy enough, you can add more chili flakes. If it's too salty, you can add a bit of water. Adjust the seasoning to your liking.

Cover the jar with a lid and let the Doubanjiang continue to ferment for 1-2 weeks. The longer you ferment it, the stronger the flavor will be.