Stir fry fail!

DH cut up the veggies (onions, celery, broccoli including stems, bell pepper, carrots) and pork for a stir fry this afternoon and I cooked it, using my enamelled iron Dutch oven instead of our stainless steel wok.  Well, I mistimed my veggies.  Usually I brown the meat then remove it and add the onions, celery and pepper, which I did tonight but the pepper turned mushy.  I then added the carrots and broccoli stems and steamed them for too long since they ended up overcooked.  Then I added the pork back in along with the broccoli florets.  I have to remember to add the florets earlier and use the pepper later in my next stir fry.