Maria, good on you for making the switch to raw! The changes in the litter boxes and the cats themselves are really noticeable aren't they.
I've gone from dry to canned to full-frakenprey, and now we are on half raw half canned (only because one of my girls, Rochelle, simply cannot live without her canned...so I compromised.
I've never had to do supplements, as I've only feed whole organs, bone, and never cooked my meats before hand. But I can tell you that even a small amount of the cooking process can cause some of the nutrients in the food to decay...obviously the longer you cook, the more nutrients are lost. A quick sear shouldn't be too much of a problem though. Just remember to never use a microwave to cook the food, and if you do decide to do bone, remember never to cook it, as cooked bone can splinter and cause issues inside of your cat.
Also, I know you mentioned being very close to vegetarian (I can understand not wanting to mess with raw meats!), but if you wanted to do a ground mixture, you could ask your local grocer or butcher if they would grind the meats and bone together for you...that way you just add your supplements and yer good to go! But you won't be able to cook it this way. Bone powder can be an option, but honestly, nothing beats real un-cooked bone, as the marrow is also very healthy. I used to do an eggshell powder (I toasted eggshells in the oven and then ground them super fine), but again, eggshells aren't real bone, so it's not the best way to go about it.
I'd definitely give some added taurine though, and if you don't want to deal with a taurine supplement or give real raw hearts, I highly recommend a freeze dried treat. I give my girls Bravo! brand Freeze Dried Turkey Hearts and they go crazy
for them. It's a nice way to give some added taurine without all the mess.
As for the canned, I stick with the best I can get and afford, all grain-free, and most are organic. Besides Rochelle's deep seeded love for the stuff, I also feed the canned to ensure they are getting enough water in the day...Rochelle and Alice are notorious for not drinking enough, so a little added water in their canned goes a long way.
Best of luck to you and your Tiger!