Notes on Vichyssoise

I have a tendency to hyperfixate on specific dishes, iterating on making and remaking them over and over again until I have a recipe (or, at least, a general set of preparation principles) that I like enough so that I consider the dish personally “solved”. In grad school I did this for (“Hainanese”) chicken rice, zhu bi png, sous vide chashu, ma la gan guo, and jambalaya¹; I've just come off doing the same for vichyssoise. Again: recipe first, notes later.

Recipe (4 servings)

Gather:

• 4 US cups stock (chicken works, but I have had success with mushroom, or generic veggie broth)
• 3 potatoes, peeled and cubed
• 3 to 5 leeks, thoroughly washed and thinly sliced; whites only (save greens for other dishes)
• Chives
• Preferred spices
• 2 tbsp Butter
• Dairy (optional)
• Alcohol (optional)

Procedure

1. In soup pot, sweat leeks in butter until soft; at least 10 min under high heat.
2. Add potatoes and alcohol if using. Turn heat down and simmer for about 45 min
3. Puree with immersion blender until smooth. Salt to taste, and add other spices and dairy as needed.
4. Consume either immediately or refrigerated, dressed with hearty amount of chives.

Notes

• I really like Yukon Gold potatoes most of the time, but they have never failed to disappoint me whenever I have attempted to make soup out of them --- it always comes out too thin. I have had some reasonable success with Russet potatoes, but I think using white potatoes (the semi-waxy kind that works very well in stews) has given me the best result so far.
• Many recipes for this that I've seen just call for black pepper, which works OK. I found that blitzing in some lao gan ma chilli crisp flakes (not too much, maybe half a tbsp for the whole pot) suits my palate a lot. Other things I've tried adding include (a) immersion-blending about 100g of pancetta² into the soup, which I really liked; a similar if somewhat inferior effect was achieved by using half that amount of Spanish chorizo instead; (b) fresh-grated nutmeg; (c) a bit of thyme (removed before blitzing) and a few mushrooms (not removed before blitzing); (d) a couple tbsp of glutinous rice, which thickens the soup considerably upon pureeing but doesn't substantially alter its flavour; (e) leftover guac, which was interesting but which I also don't think I'll be doing again too often.
• I don't always use dairy for this (especially if I thicken the soup with rice). The NYT recipe that I originally started using called for heavy cream, which of course works pretty well. I have also tried Greek yoghurt (reasonable) and cream cheese (good, but you really feel it in your arteries) as dairy thickeners. I have also been asked to try using straight-up mascarpone but haven't been able to justify the expense. I additionally tried emulsifying olive oil into one batch of this but the emulsion refused to hold; it only stopped breaking after I also blended a couple slices of Kraft singles into the soup.
• I almost never use alcohol for this. I have tried white wine (was OK), beer (just no), shaoxing wine/花雕酒 (surprisingly not terrible, especially with the chilli crisp), and soju (undetectable). I have been told sherry is common, but I have no other kitchen use for that and am unlikely to purchase any in the near future.