익다 is what food does over heat — it becomes cooked by itself, so you never 익다 something (that would be 익히다). -게 says how it came out, and here the adverbs are all doneness words: 노릇노릇하게 익은 베이컨 (bacon done golden brown), 바삭바삭하게 익었고 (came out crisp), 완벽하게 익었어, 이븐하게 익은 소고기 (evenly cooked beef, from English 'even'). The same verb covers skin reddening and fruit ripening — 안 그러면 붉게 익어.