I've been hesitant to share this place, because a part of me wants to gatekeep this one. If you ask me to share my number one tip for food in Sevilla, without a doubt I say Dos de Mayo. I discovered this authentic tapasbar 7 years ago - it was the first bar I came across while looking for a place to eat. And it unexpectedly became my favourite bar in the whole city. This place has a vibrant Spanish atmosphere, the best vermut casero (homemade vermouth) and lots, lots of delicious tapas and platos on their menu.
PS: the waiters speak mostly Spanish (and some of them also some basic English) and you will most likely have to wait a bit for a free spot - but that's exactly why I love this place so much.