Get five medium bowls and line them up
If it's not shredded, shred the cheese, and put it into the fourth bowl.
2 lb (possibly shredded) cheese
On the cutting board, dice the red and green peppers, into the size you'd like to find in your quesadillas (about 30 min)
10 oz whole green bell peppers, 10 oz whole red bell peppers
Put the first, empty medium bowl on the kitchen scale and zero out its weight
Put all the diced peppers into this first medium bowl and note their weight. About a third pound of pepper should have been discarded material, so we should have roughly 14 oz left Take 2 cups of the peppers and put them into the second medium bowl.(There should now be about 6 oz left in the first medium bowl. If not, adjust the amounts to get to a roughly 3:4 ratio between first and second bowls.) On the cutting board, dice the onion into the same size as the peppers
10 oz whole onion
To the first medium bowl, that has the ~6oz peppers, add the same weight of diced onions.
Line a large baking sheet with parchment paper
On the cutting board, dice the chicken into cubes the size you'd like to find in your quesadillas (10-15 min)
2 lb skinless, boneless chicken breast
Put the raw diced chicken into the fifth medium bowl; the third bowl is still empty for now: that's where the cooked chicken will go.
Add the packet of fajita seasoning and toss with the raw, diced chicken
1 packet fajita seasoning