Prep the vegetables – slice the celery on a bias into ½” thick pieces, dice the red pepper and red onion into 1” pieces, trim the broccoli into 1” pieces, and thinly slice the scallions.

Slice the salmon into 2” pieces and season on both sides with kosher salt and black pepper. 

Add the ¼ cup of cornstarch into a shallow bowl or plate. Coat each piece of the salmon with cornstarch, then set aside. 

Heat a pan on medium high heat. Add a tablespoon of neutral oil, then add an even layer of the coated salmon. Cook for 2-3 minutes, then flip the salmon and cook for another minute. Remove the salmon from the pan and set aside (can be the same plate as before as we are going to continue to cook the fish). 

Add another tablespoon of neutral oil then add all the vegetables to the pan. Cook for 3-4 minutes. Add the garlic and give this another mix. 

Make the cornstarch slurry by combining the water, broth, and 1.5 tablespoons of cornstarch. 

Add the cornstarch slurry and give everything a toss. 

Add the ketchup, vinegar, soy sauce, and sugar to the vegetables, and give everything a stir. 

Add the seared salmon back in, and cook for another 2 minutes on medium heat. 

Taste, adjust seasoning as desired, and serve over rice.