Whisk yolks and the teaspoon of water in a heatproof bowl over barely simmering water until pale, doubled, and ribboning — 2–3 minutes. The bowl must never get too hot to touch.
3 min — timer available in cooking mode
Why this works
You are gently cooking the yolks to thickening (around 65°C) without scrambling them. If you see any graininess, pull the bowl off and whisk hard.