It turns out that the dangerous part of visiting B's sister's house nowadays is the impossibility of leaving without being weighed down with a bag of gift tomatoes. There are tomato plants there now, which produce more than can be consumed locally.
Sister's husband likes to munch on them raw, but I don't like them that way, and B is allergic to the raw. There was nothing for me to do but to learn how to make marinara sauce. I downloaded about 5 divergent recipes, choosing the parts I liked best - 20-minute cooking time, not 90 minute; 7 cloves of garlic, not 2 - but basically it was simple. Saute onions and garlic in olive oil, add the tomatoes and a little wine and whatever herbs you like, and it's done.
What was interesting to me was learning how to peel the tomatoes. First you cut out the stems with a knife - some recipes say to do this afterwards, but they're wrong - and make a little notch in the base with the same implement. Then you give the tomatoes a quick sauna: 30 seconds in boiling water, scoop them out and dump them for a minute in ice water, and the skins slip right off. I wonder if this would work for humans.
I found an odd-appearing implement in the miscellaneous kitchen-tools drawer - it resembled a realization of something from a wiring diagram - that looked as if it might do for crushing the peeled tomatoes, at which it worked splendidly. I learned from B later that it was in fact a potato masher, something I've never had any use for.
There was a bit more sauce than I needed for my regular baked ravioli dish, so two days later I turned the remainder into ketchup (add a little vinegar and maltodextrin, heat and let reduce slightly) and used it as glaze on my newfound turkey meatloaf recipe.