How to Make It
Stir together shallot, vinegar, granulated sugar, and 1 teaspoon salt in a small bowl until salt and sugar dissolve. Let stand at room temperature 45 minutes.
Meanwhile, preheat oven to 350°F. Stir together brown sugar, white and black sesame seeds, and gochugaru in a small bowl. Arrange bacon slices in a single layer on a large aluminum foil–lined rimmed baking sheet. Bake in preheated oven 20 minutes; flip bacon slices, and sprinkle with brown sugar mixture, pressing to adhere. Bake at 350°F until sugar has melted, 7 to 10 minutes. Transfer cooked bacon to a wire rack set inside another foil-lined rimmed baking sheet; let cool. Coarsely chop bacon, and set aside.
Meanwhile, stir together 8 cups water and rice in a large, heavy-bottomed saucepan. Bring to a simmer over medium-high; reduce heat to medium-low, and cook, gently stirring bottom and edges of pan with a wooden spoon to prevent sticking, until congee is thick and creamy, about 45 minutes, adjusting heat as needed to maintain a gentle simmer. Stir in remaining 1 1/2 teaspoons salt.
Ladle hot congee into 4 serving bowls; top each with 1 egg yolk. Top evenly with chopped bacon and pickled shallot, and drizzle with toasted sesame oil. Serve immediately.
Look for gochugaru (coarsely ground chile flakes) at your local Asian market.