Heat the olive oil in a large, heavy based pan on medium-high heat. Add the onion and garlic, cook, stirring for 1-2 minutes until softened.
Add the beef mince, cook, breaking up the beef as you go for 3-4 minutes until the beef begins to brown.
Add the teriyaki sauce (store-bought or homemade) directly to the beef. Cook, stirring for a further 1-2 minutes until the sauce has thickened slightly.
Combine the corn flour and water and add it to the pan, cook for a further 1-2 minutes until the sauce is thick and glossy.
Remove beef mix from pan.
Add a little water to deglaze pan and then add in broccoli and green beans. Stir to coat in remaining sauce and add a little extra water to steam veg through. Cook until just soft. And remove from heat.
Divide the steamed rice, beef mix and green veg across four bowls. Sprinkle with the sesame seeds and edamame. Spoon remaining sauce over each serve.