Pour the mung beans into a heat-safe bowl. Pour hot water over the beans and let it soak for at least an hour.

Add the soaked mung beans, water and coconut milk into a high speed blender, and blitz until smooth.

In a medium bowl, mix the rice flour, cornstarch, salt, turmeric, coriander, porcini mushroom powder and garlic powder. Pour the liquids into the flour mixture and stir until you get a silky batter. Mix in the sliced scallions, cover and refrigerate for at least an hour.

Drain the tofu and wrap a layer of paper towels around the tofu block. Place the tofu on a plate and press it with a stack of plates placed over the tofu block. Let it sit for 15 minutes.

Remove the paper towels and slice the tofu along the length of the tofu block, making 8 slices. Take each slice and cut in half to get 2 thin rectangles. Cut each rectangle into 5 cubes. You should have about 80 tofu cubes when you're done.

Heat a large pan with about 2 tablespoons of olive oil over medium-high heat. When the pan is hot, add the tofu and cook until a few sides are golden brown, about 6 minutes. Flip the tofu cubes to get the other sides browned, but it's not necessary to brown all sides. Sprinkle a small pinch of salt over the tofu and stir. Turn off the heat and leave the tofu in the pan.

Heat about 1 to 1 1/2 teaspoons of olive oil in an 8-inch skillet over medium heat. Add a few slices of onions to the pan and cook for about 1 minute. Sprinkle 6 to 8 tofu cubes into the pan. Imagine there is a line running down the pan and arrange the onions and tofu on either side of that line, leaving about a 1-inch gap in between. This will make it easier for you to fold the banh xeo in half later. Pour a scant 1/4 cup of batter into the pan, swirling the batter to make sure that it covers the entire surface area of the pan. Enjoy the sizzling noise!

Once the outer edge of the banh xeo is slightly cooked, this takes about 20 to 30 seconds, add the mung bean sprouts to one half of the cake. Lower the heat a bit and cover the pan with a lid. Leave the lid on for about 1 minute. This helps soften the mung bean sprouts. Remove the lid and cook for another 1 or 2 minutes, until the edges are browned. Using a rubber spatula, gently lift the half of the banh xeo without the mung beans and flip it over the other half. Turn off the heat. Transfer the banh xeo to a plate and repeat with the remaining batter.

Add all the ingredients for the sweet chili sauce to a saucepan. Stir until the cornstarch is dissolved.

Heat the saucepan over medium heat. When the sauce starts boiling, let it simmer for about 3 minutes. Turn off the heat.

Serve the banh xeo with the sweet chili sauce, mint leaves and cilantro.