Mushroom Noodle Soup

Ingredients

• 2 tbsp butter
• 1 large onion, diced
• 1 1/2 lbs mix of crimini, shiitake, oyster mushrooms
• 1/2 cup sake
• 1/2 cup mirin
• 1 1/2 quarts of water
• 4 scallions
• 1 tbsp of kosher salt
• 2 tsp soy sauce
• 2 tsp rice vinegar
• 1 piece of ginger (approximately the size of your thumb)
• 1 pound of homemade or storebought noodles
• 4 eggs
• Sliced pickles (like turnips or daikon)
• Scallions
• Sesame seeds
• Chili flakes