Fry the egg - Beat the egg until homogenous, season it with a pinch of salt, and cook it in a pan on medium heat with a bit of neutral tasting oil like canola until just set. Like when you cook scrambled eggs or an omelette. Once cooked, set aside on a clean bowl or plate.
Fry the chicken - In the same pan fry bite-sized and seasoned pieces of chicken or whatever protein you are using until cooked through on medium-high heat. Once cooked set aside on a clean bowl or plate. If you are doing vegan fried rice, then skip to the next step.
Fry the onion and garlic paste if using - Same as before in a bit of canola oil or something similarly neutral tasting. Cook until just soft and starting to brown a bit.
Fry the vegetables - Add the vegetables and stir fry for 4 minutes until they soften a bit.
Add the cooked rice - Add your rice and give the whole thing a mix-through.
Season - Add the soy sauce, sugar, sesame oil, oyster sauce(if using) and give it another stir-through.
Add the cooked egg and chicken - Mix in the cooked scrambled egg along with the cooked chicken or other protein if you are using it as well as the toasted sesame seeds.
Finishing touches - Give it one more stir-through and taste it for seasoning and balance, adjusting as needed. When you are happy with it, sprinkle with some freshly chopped scallions and serve.
Notes
Always use cooked and cooled rice. Day-old rice makes the best results.
Always cook your proteins first if using them.
Do not scramble the egg by mixing it with other ingredients. It has to be done separately.