How to Make It
Place eggs in a medium bowl. Gradually whisk in 11/3 cups dashi, soy sauce, and sake. Pour liquid through a fine wire-mesh strainer into a bowl. Discard solids. Divide liquid among 4 small heatproof bowls or ramekins. Cover tightly with plastic wrap.
Bring 1 inch of water to a simmer in a pot fitted with a steamer basket over medium-low. Add bowls to steamer. Cover and steam until custard is set, about 15 minutes.
Unwrap custards. Garnish with uni, crabmeat, mushrooms, scallions, and cilantro, if desired. Combine remaining 1 tablespoon dashi with yuzu ponzu, and top custards evenly with mixture. Serve immediately.