I started out my first vampire household today. I found that life as a vampire is rather more complex due to "thirst", and eating regular food doesn't do a thing for a vampire.

So far my sim doesn't know how to find the (something) recipe as blood replacement to quench thirst yet. He has to take a detour after work and take considerably longer time than eating to "raid hospital" to stay alive.

Anyone has a good strategy for new vampire household?

I'm not entirely sure whether I understood your question, but there are various ways to "feed" a vampire without having to bite other Sims:
1. Plasma Juice is available for free from any fridge in town. Place some additional fridges on community lots. This has the added advantage of also being good for your nerves or ears, respectively, as NPC Sims have this habit of arriving on a community lot and being hungry. A fridge present and the whining will abate.
2. Plasma Fruit is available in the grocery for 30§. Vampires can eat it right away, plant it (level 7 Gardening required), or use it for cooking. Every meal that recognisably uses fruit (pancakes, fruit cobbler, crepes etc) will satisfy a vampire's thirst need when eaten.
3. Every food register and the food truck sell Plasma Soup.
4. Eating out at the bistro or diner will also satisfy the thirst need, plus gives a bonus with the same moodlet you'd get from biting someone.
5. This bonus will also be given by perfect Plasma Fruit (and 1 or 2 quality levels below perfect)
6. Buydebug has Plasma Fruit plants available. Plant these on community lots and harvest them from time to time. The additional advantage is that Plasma Fruit plants on community lots or residential lots you do not play will not wither.
7. This lead me to my next strategy. My Sims' neighbour is a gardener. I had her plant some ten Plasma Fruit seeds and now she caters for my vampire family, so-to-speak.
8. Feed an Omniplant with Plasma Fruit and it will yield more fruits than the regular Plasma bush.
8. Nectar that contains Plasma will also fill the thirst bar.

Plasma fruit, that is the word I was looking for.

Ah right, I remember buying Plasma fruit from one of my human sims before off lunch truck.

You can steal stuff off your neighbor's plants? That is rather convenient. Force your neighbors to "unknowingly" plant the fruit without having a need for it and have the vampire reaps the reward.

Thanks for showing "Plasma Fruit is available in the grocery for 30§. Vampires can eat it right away, plant it (level 7 Gardening required), or use it for cooking. Every meal that recognisably uses fruit (pancakes, fruit cobbler, crepes etc) will satisfy a vampire's thirst need when eaten". I had been hunting for the actual "Plasma juice" recipe as a cooking recipe.

Plasma fruit nectar is a great thing to have. Try and put 1 life fruit, 3 flame fruit and 6 plasma fruit. Along with the sated moodlet (or whatever) you get the additional "full of life" and some moodlet to do with the flame fruit, like flamey or cosy.. I think you get sugar rush with all nectar too, so that's an added bonus..
I personally just like getting them to feed properly