Not much beats a plate of asparagus slathered in hollandaise. But if you fancy a more eco-friendly swap, mayo is the answer. That’s because the carbon footprint of butter is four times higher than olive oil and twice that of rapeseed oil.
This homemade mustardy mayo is easy to make, as long as you’re willing to give your whisking arm a workout! Have it with boiled eggs and toast for a simple but excellent dinner.
Why is this eco?
If you are going to make hollandaise or cook anything with butter, you’ll be doing much better by the environment by using olive or rapeseed oil instead.
About 7.3kg of CO2/equivalent is produced per kg of butter while olive oil produces 2.3kg (more if it comes in a smaller bottle). The study is calculated with butter from American dairies but this journalist uses Carbon Trust numbers to estimate that UK butter is actually higher at 9.4kg CO2/eq.
CO2/eq is a way of measuring all greenhouse gases under one common unit. For example, methane produced by cows can be measured in CO2/eq. These carbon footprints were calculated by adding up the greenhouse gases produced in all stages, from farm to packaging and transporting.
- 1 egg yolk
- 1 tsp white wine vinegar (or lemon juice)
- 1 big tsp Dijon mustard
- Big pinch of salt
- 75ml British rapeseed oil, or olive oil
- 1 bunch asparagus (about 12 spears)
- Chilli powder, paprika or black pepper to taste
Whisk the egg yolk for a whole minute with the vinegar, mustard and salt.
Drizzle in just a teaspoon of oil and whisk for another whole minute. Add another teaspoon and whisk for one more minute.
Now pour in a thin steady stream of the remaining oil, whisking constantly with your other (aching) arm.
Steam the asparagus for 5 minutes or up to 8 if it’s thick. I use a steamer or a sieve with a lid on, placed over a pan of boiling water.
To serve, spoon some mayo over the asparagus and sprinkle over chilli powder, or dip spears in a ramekin of the stuff.
Use up any leftover mayo in sandwiches or in a potato salad. Store it in the fridge for up to a week with clingfilm pressed against the top of the mayo to stop a skin forming.