Sydney Smith's Salad Dressing

TO make this condiment, your poet begs
The pounded yellow of two hard-boiled eggs;
Two boiled potatoes, passed through kitchen sieve,
Smoothness and softness to the salad give.
Let onion atoms lurk within the bowl,
And, half suspected, animate the whole.
Of mordant mustard add a single spoon,
Distrust the condiment that bites so soon;
But deem it not, thou man of herbs, a fault,
To add a double quantity of salt.
Four times the spoon with oil from Lucca brown,
And twice with vinegar procured from town;
And, lastly, o'er the flavored compound toss
A magic soupcion of anchovy sauce.
O, green and glorious! O herbaceous treat!
'T would tempt the dying anchorite to eat:
Back to the world he'd turn his fleeting soul,
And plunge his fingers in the salad bowl!
Serenely full, the epicure would say,
"Fate cannot harm me, I have dined to-day."

2 hard-boiled egg yolks
Two boiled potatoes
1 tbsp finely chopped onion
1 tsp mustard
1/2 tsp salt
4 tbsps olive oil
2 tbsps vinegar

Mash the egg yolks and the potatoes, mix in the other ingredients, beat. Add to coarsely chopped romaine lettuce. (Who has anchovy sauce in their kitchen cupboard?)

Update: I've just made it, and it's delicious. You could eat it on its own. I left out the mustard, salt and pepper but it's just as nice without. I used new potatoes, Palestinian olive oil, Aspall balsamic vinegar and a sweet shallot.