Combine water, garlic, ginger, and onion in a large stock pot.

Bring to a simmer.

Reduce heat and maintain a simmer for 40 minutes.

While broth simmers, fill a saucepan with water and bring to a boil.

Reduce heat to a simmer.

Lower eggs into the water one at a time.

Cook for 7 minutes for barely set yolks.

Remove eggs from hot water and run under cold water until cool.

Peel the eggs and halve lengthwise.

Season with salt and pepper.

Fill a large pot with water and bring to a boil for noodles.

Reduce heat to a simmer.

Remove garlic, ginger, and onion from the broth using a slotted spoon or strainer.

Discard the vegetables.

Add soy sauce, sake, chile sauce, sesame oil, sugar, and salt to the broth.

Stir well.

Cover loosely and simmer for 10-20 minutes more.

Return simmering water to a boil.

Add noodles and return to a boil.

Cook noodles uncovered, stirring occasionally, for 1-3 minutes or until tender yet firm to the bite.

Drain the noodles and divide between 4 large bowls.

Add shrimp and scallops to the simmering broth.

Cook until opaque, 3-5 minutes.

Ladle broth into bowls to barely cover the noodles.

Add equal amounts of shrimp and 1 scallop to the center of each bowl.

Place a portion of bean sprouts on the side of each bowl.

Place 2 soft-boiled egg halves, yolks up, on the noodles in each bowl; keep eggs above the broth.

Garnish with scallions.