I am new to the kitchen and a little paranoid when it comes to cooking. Today, I bought what is being called 'grade 2' tuna from whole foods, and asked if it was okay to just sear it and eat it still raw in the middle. The fish munger said that it was alright. I just cooked (and ate) the tuna, but noticed numerous white stringy things (?) in the flesh. I have eaten tuna sushi, etc numerous times and have not noticed this. Is this just something that is normal to tuna or was my tuna not so fresh. Should I remove these 'strings' next time I cook tuna. Is it ok to eat 'grade 2' tuna only seared, not cooked all the way through.
Thanks for all future responses.