Using an electric pressure cooker, press Sauté. Once the pot is hot, add the oil. Sauté the onion, white parts of the green onion, and ginger for 2-3 minutes. Add ground beef and brown until cooked through.

Cancel sauté mode. Add tomatoes, salt, soy sauce, dark soy sauce, oyster sauce, sugar and ketchup.

Close and lock the lid, making sure the steam knob is on Sealing/Locked. Pressure cook on high for 5 minutes.

Once the cooking is done, release the pressure by quick or natural pressure release.

Press Sauté to simmer the sauce. In a small bowl, dissolve the cornstarch in the water and stir the slurry into the sauce. Heat through until sauce thickens.

Add the green parts of the green onion and heat through.

Heat a large wok or frying pan on medium heat. Add 1 tablespoon vegetable oil and onion, white parts of the green onion, and ginger and stir fry for 2-3 minutes. Add the ground beef and brown for 2-3 minutes until cooked through.

Stir in tomatoes, salt, soy sauce, dark soy sauce, oyster sauce, sugar and ketchup. Cover and let simmer for 20 minutes.

In a small bowl, dissolve cornstarch with cold water to make a slurry. Stir the slurry into the sauce and heat through until the sauce thickens.

Add the green parts of the green onion and heat through.