Onion to carrots to celery ratio should be 1:2:2, so there should be half as much onion as there is carrots, and there should be the same amount of celery as carrots
Heat oil until slightly smoking
Drop celery and carrots, stir fry until celery becomes translucent, then remove from pan
Drop onions, and cook until fragrant
Deglaze with white wine, meat stock, or water, and add celery and carrots back into the pan