Vegetable Tempura Udon

Name: Vegetable Tempura Udon
Prep time: 45 min
Cook time: 15 min
Total time: 1 h
Cuisine: Japanese
Ingredients: 200ml cold water chilled; 100ml sparkling water chilled; 30g potato starch; 150g weak flour (cake flour or all purpose) + extra for dusting; 1 medium egg chilled; 4 shiitake mushrooms stems removed; 1 large eggplant (or 2 small) cut into wedges and soaked in cold water; 8 perilla leaves (ooba/shiso); 4-8 stalks asparagus; Oil for deep frying (vegetable, canola, peanut or white sesame); 1 litre (4 cups) dashi (I recommend my homemade dashi recipe / plant based dashi); 5 tbsp (75ml) soy sauce; 2 tbsp (30ml) mirin; 1/2 tsp salt; 4 portions udon noodles; 8-12 slices kamaboko (omit for vegetarians); Spring onion (scallion) to garnish; Shichimi togarashi (Japanese chili) to garnish