I love fish and courgettes, tomato etc. don't in an oven.  I'm gonna be on holiday in a third world country where people do not have ovens in their home and just usually use a stove of some sort. How do people in this countries get food cooked, like an oven, grill etc. or are my only options stove top frying and wet heat methods? 
Maybe they don't.  You can't replicate roasting on a stove top. With a grill pan, you can get in the ball park of grilling, but you would miss the major flavor contributor resulting from drippings hitting hot coals or grill burners. Rather than trying to replicate something you do at home, I would suggest, that when on holiday, you embrace the culture of the place you are visiting.  Leave your favorites from home behind, learn about the culture of the place you are going, participate, and learn something new.  You can return to the methods you use when you come home. 