Peanut butter becomes a dressing only after enough liquid goes in. A thick spoonful may taste lovely by itself, yet pull a bowl of noodles into one stubborn knot.
For two servings, whisk two tablespoons smooth peanut butter with a tablespoon soy sauce, a tablespoon lime juice, and a teaspoon maple syrup. Add warm water a spoonful at a time until it flows readily from the whisk. Stir in chili if wanted.
Cook 160–180 g egg-free noodles according to their packet. Toss with the dressing and thin strips of cucumber and carrot. A splash of water loosens the mixture if it starts tightening before you sit down. Add chopped spring onion just before serving.
Do not make this for someone with a peanut allergy by merely removing the garnish; the dressing itself contains peanuts. A different seed-based dressing is a separate option only when its ingredients and preparation are suitable for that person.