Well, starting a new restaurant is so hard. I started my own like one month ago and I'm doing "o,k", my situation is quite similar to yours.
I'm civil engineer with a 9/5 job and my sister was in a shitty job so we decided to start this business. one huge advantage: She owns a house with space enough to run a restaurant with 32 people at the same time. Another advantage:We live in Colombia where you can pay 10 dollars A DAY for someone who washes all those dishes and you pay 20 to 25 dollars a day for someone who cooks. I was a waiter and manager with my sister. I know lil things about food specially about what you can and you can not do. I learned to make crepes through the internet and I taught my sister also and then we started. Once you are inside a kitchen you start to wonder if you made the right choice, I'm still wondering hahaha, the food business is a hard one but if you are tired of a job where you don't feel happy, I'd say: go for it. After our first month I was able to earn some money but I've gotta say that if we were paying rent, we would be really scared as the business is not gathering the money we thought it would.
another advice: DON'T QUIT to your current job, trust me: you will need another income for a while, and if you find a job washing dishes, work there for 3 to 4 months...2 years is way too much....if you come to Colombia you can see how we do thing here.
Another big advice: AFTer you have decided your location, ask yourself: what is missing in this area that I can bring?? I highly doubt a steak is the answer, My answer was: crepes and well...I was wrong but my "chef" saved me and changed the menu. Now we are doing regular lunchs in the day and homemade hamburgers and crepes in the nights. I was able to correct my mistake as my sister, as I told you before, owns the property ...but with rent you should be more careful..
Best wishes and let me know if you wanna keep in touch