Rinse the rice thoroughly and drain well. Toast the rice in a dry pan over low heat until it turns slightly golden. Toasting the rice before cooking makes the congee more fragrant and flavorful. Trim the ends off the straw mushrooms, wash, drain, and sauté until cooked.

Bring a pot of water to a boil (enough to cover the duck), then add the duck. Start with high heat, then reduce to low so the duck cooks gently and the broth doesn't evaporate too quickly. Add crushed ginger to the pot to remove odors and add fragrance. While boiling the duck, leave the lid off and skim off any foam regularly to keep the broth clear and naturally sweet.

After boiling the duck for about 15 minutes, add the rice to the pot. When the duck is tender, remove it and let it cool. Add the sautéed mushrooms to the congee. If the rice hasn't fully opened up when you remove the duck, continue cooking until the grains are just tender and the congee is creamy but not mushy. Season to taste.

Shred the banana blossom and water spinach very thinly, wash, drain, and chill in the refrigerator for about 1 hour to keep them crisp. Julienne the carrot and chop the Vietnamese coriander. For the salad dressing, mix vinegar and sugar in a 1:1 ratio with some thinly sliced shallots. When ready to eat, toss the shredded banana blossom, carrot, water spinach, and Vietnamese coriander with the dressing, sprinkle with fried shallots and roasted peanuts, and serve with the duck congee.

Ladle the duck congee into bowls, sprinkle with green onions, the white parts of the green onions, fried shallots, and black pepper. Arrange the duck pieces and dipping sauce on the side and enjoy.