any suggestions for restaurants near the Roundhouse Theatre in Camden area of London?
Depends on your budget and preferences, but there's a number of nice restaurants in Primrose Hill, which is just a short walk away. Gastropubs the Lansdowne and the Engineer on Gloucester Ave. both have excellent food. There's a small french restaurant L'Absinthe on Chalcot Road. There's also a newish Italian place on Princess Road called La Collina. Haven't been, but heard good things.
In Camden proper, there's Market on Parkway for modern British. El Parador near Mornington Crescent for excellent tapas.
There's some decent but perhaps less chow-worthy spots within a block or two of the Roundhouse on Chalk Farm Road. Muang Thai is almost directly across the way, Yum Cha has some decent Cantonese, and also a few good Malaysian dishes on the menu (and half price dim sum if you go M-W evening before 7). Belgo Noord is a chain that does Belgian beer and mussels. Nothing too refined, but quite decently priced if you just want a bucket of mussels and a good beer.
Just across the road, I'd second Belgo (although I must admit I haven't been there in a few years) for Moules Frites, and for dessert Marine Ices, which has been a North London destination for decades and still has delicious intense creamy gelato. Yum.
If you can stagger slightly further, in Primrose Hill there are 2 lovely Greek restaurants: Lemonia and Limani. For some reason Lemonia is much more famous, but I actually prefer Limani (and they don't rush you out so fast - although if you're doing pre- post-theatre, that may not be an issue for you).
And if you're in a car, then a 3 minute drive up hill brings you to Belsize Park, and there are lots of quite nice (chain) restaurants there, such as GBK and Pizza Express.
When I lived in Belsize Park my favourite sushi restaurant was Ikura located on Haverstock Hill, just before England's Lane. Beware, it can be pretty quiet inside sometimes. May not be the place if you are looking for something more lively but I always thought the great sushi and lovely staff made up for any lack of ambiance. A short 7-10 min walk from The Roundhouse.
Cottons has decent Caribbean dishes and can be good before or after a night out. Includes extensive rum selection.
Also second the recommendations above for Market and El Parador, both excellent.