Stir Fry

The Sauce 
3 parts soy sauce
2 parts mirin
2 tsp corn starch
Dash of Worcestershire

Other Stuff
flank steak
onions
bell peppers
rice
garlic

Preparation
Wash the rice and get that cooking, whether it be in a pan on the stove or in a rice cooker. Do the rest of the prep after the rice has begun cooking.

Slice the flank steak into thin strips, against the grain of the meat Slice the onions and bell peppers
Mince the garlic
--then--
Rub the sliced flank steak with minced garlic and kosher salt. Let it sit together for ~10 minutes. Don't use too much salt!
Mix the sauce together in a dish. You'll probably need to mix it again just before pouring into the pan.

Cooking
Cook the meat on ~medium heat in some hot oil.
Throw the onions and bell peppers in another pan in some hot oil. Leave the pan on medium-low heat. Add some salt. If cooking other veggies, prepare similarly.
Once the meat is cooked 3/4 to your liking, add the veggies, and toss a bit. Stir the sauce again, then pour into the pan with everything else. Stir and stir. Cook for a few more minutes, and it will be ready to go!

Serving
Serve alongside or on top of rice.