To make the pork belly: Preheat an oven to 350 degrees F. Heat a smaller (just large enough for the pork belly to sit in) dutch oven over medium heat. Add pork belly fat side down and sear for 5 minutes or so, until browned. Flip the pork belly and add the beer, soy sauce, mirin, hoisin and ginger and bring to a simmer. Turn off the heat, cover and place in the oven. Braise for 2 hours, or until tender. Remove from the oven, cool to room temperature. Transfer to the pork belly to a plate, cover and refrigerate until firm.

To make the cucumbers: mix rice wine vinegar with sugar, salt, sesame oil and seeds until the sugar and salt have dissolved. Add cucumbers and let marinate for 30 minutes to 1 hour.

Preheat an oven to 450. Once the pork belly is firm, cut into 1/4" slices and place on a silpat or foil lined baking sheet. Mix together soy sauce, hoisin, and sriracha and brush over the pork belly slices. Sprinkle with sesame seeds. Place in the oven for 10-12 minutes, until pork belly is golden brown. Spread a little kewpie into each steamed bun, add a slice of pork belly and top with marinated cucumbers, greens onions and cilantro.