Beef with Broccoli and Choko Stirfry

Beef with Broccoli and Choko Stirfry Ingredients: 

1 kilo beef sirloin steak, cut into thin strips/slices 
1 large size, broccoli, cut into serving pieces, stem thinly sliced, separate
2 medium size chayote/choko, peeled, deseeded, sliced into thin strips
1 small size red or yellow bell pepper, cut into strips
2-3 thumb size ginger, peeled, cut into thin strips
1 small bundle leeks, cut into 2” lengths
1 medium onion, coarsely chopped
2-3 thumb size ginger, peeled, cut into thin strips
2-3 cloves garlic, finely chopped
1/4 cup soy sauce
1/4 cup oyster sauce
1/4 cup cornstarch
salt and pepper
cooking oil