bgr topics usually get messy and unproductive in this forum.
but I'm usually more straightforward so I'll just do a Q&A for you directly
1st things first, you don't need an excuse or tactic to ask someone out unless there's obstacles like her parents are there with her.
2) girls are not going to help you to ask them out unless they're lesbians or butches.
3) if you simply wanna ask someone out for a meal , just go "hey, are you hungry? I'm going to eat at this great makan place , healthy, cheap and good, would you like to join me" thats it. hungry is the keyword cos if you're going to eat after 7pm or right after a meal,the girl is going to tell you she's not hungry, or it's too late I don't want to eat too much too fattening etc. and be a gentleman and say "it's on me. c'mon don't say no to my sincerity please" or "good food must be consumed with good company"
it's how you portray yourself instead of ctrl c ctrl v some lame pickup line straight from the internet. confidence, gentle persuasion and sincerity will shine the way.
whatever goes with your style or if you don't have any, start practising. I used to directly approach women at cafes/fastfood/outside. whether they reject or accept my approach, it's experience and I got good at it eventually. at least, numb to rejections.