Washing eggs removes the “bloom,” the natural coating on eggs that preserves the eggs’ moisture and protects the interiors from bacteria. In Europe and the UK, eggs, even factory-farmed eggs, are not washed. In the US, however, factory chickens are extremely unhealthy and live in filthy conditions, so egg-washing is necessary, but it’s totally unnecessary for eggs from a small, clean home operation. I’d still put them in the fridge though. Especially if there’s a chance some could have been fertilized.
As a general rule of thumb, you substitute 2 duck eggs for every 3 chicken eggs in a recipe. But in many recipes you can go one for one and you’ll just get a richer, moister, denser end product.
Duck eggs are fantastic for custards and omelets, great for pastas and enriched yeast breads like brioche, and wonderful in cakes, especially gluten-free cakes where their richness and sturdy protein structure help compensate for a lack of gluten. They’re also the best eggs to use for this Kerala-style egg curry: https://cookingfromheart.com/nadan-mutta-curry/
