quite a bit of butter (25g?)
a few dl of water
1 onion
sea salt
dried sage, tarragon, oregano
quite a lot of black pepper
a little Tasbasco, as usual
a little French mustard

spaghetti, boiled with sea salt (1 tbsp) and olive oil (2 tbsp) for 2 persons

Melt the butter over low heat. Add the herb and spice stuff and let simmer slowly, 5 min. or so. Add the onion, chopped, and go on boiling it in the butter until as soft as you like. Not too short.

Add a little water after 5 min. and boil a few minutes more, until the moist thickens into a sauce, fitting to fill a few plates of spaghetti.

Add salt and pepper to taste.
——

I forgot garlic, which I had intended to include, and made another little sauce out of

1 tbsp butter
1 clove garlic, finely chopped
a little Tabasco sauce (or actually, not so little)

This actually tasted better than the first sauce, and pretty much overruled it when mixed with what was on the plate, so it should have been served separately, I guess.