There are four LOKAL restaurants in Prague. The two most known are on Dlouha street and Charles Bridge. I prefer taking my guests to the Charles Bridge LOKAL because it is cave-like in its construction - I like to make people "WOW!"
I have been visiting this place regularly. It is usually excellent, whatever I have. Their Zelnečka (Cabbage Soup) in bread is exceptional, but I also like to go here when I want a salad. Also, with it being a Pilsner pub, you'll always get great beer
Historic Cafe Slavia is another highlight and one I always squeeze into my 'hit-list' for visitors... Even if just for fine coffee and cake at night with the piano playing. Slavia is opposite the National Theatre, Also, my favourite Tiramissu in Prague.
I've tried a few Švičkova on my travels, and when it's done well, it is delicious - but when it's bad, the cream and jam make it a confused mess. I believe Švejk U Kalicha has the balance just right for theirs. You'll like the building decor too.