My favourite tomato; and I don't know the name

[Altmer]

Hello, I decided to post a few photos of my favourite looking and tasting tomato. I don't know the name of it and have looked everywhere online for it--even the database on The World Tomato Society. Maybe someone will have more luck/a better eye than I.

I got the seeds from Croatia from a couple who got them from someone selling seedlings on the side of the road. The tomatoes range in weight from about 400-900 grams. They're sometimes a bit hollow inside but still juicy. My plants this year are greater than 7 feet tall (I'm Canadian so please forgive me for switching between metric and imperial measurements) and have what I think are regular leaf, just a lot bigger and fuller than any other I've seen. Last year, the excessive heat during flowering caused about 80% of the flowers to drop and plants yielded 4-5 tomatoes each, this year I'm getting 16+ each plant. The fruit shape is interesting, they're ribbed but also have an oxheart-shaped bottom most of the time. I've only had one with blossom end rot and that was this year. They also seem to have pretty good disease resistance; the oxheart and beefsteak plants next to them all have slow moving disease but these guys are quite unaffected.