This is how I feed my veggies to them. I do have a chop that is also a little bigger in pieces that will accept as well.
I add pellets (I actually have two kinds) to this and let the moisture from the fruit/veggies soften the pellets.
I started offering them this, with some seeds sprinkled on top. I made sure they didn't eat seed for 3-4 hours prior. But what made the big difference was after they refused it, they only got a little bit of seed, then was not given seed at night, for bedtime. Since they sleep at night, and morning is when they are hungriest They do best eating this in the AM .
After they were comfortable eating the chop, I did away with the seeds sprinkled in it. And used pellets instead. They took to the moistened pellets almost right away. After a week or two of this they began eating more and more of it.
Now I can introduce new foods if I use the same little plate. Because they associate the plate that I use now, with food . I never free feed them inside their cage, other wise this would not work. They get their meals on a schedule. They have actually gained weight, and their poops look healthier . Now if I let them eat seed, or just stick a bowl in the cage with just seed, their poops look stickier and almost like they are constipated. The fruit and veggies, and pellets have made a big difference by adding it to their diet, in addition to seeds. I still feed seeds, but only in the evening, or mid day AFTER they have had veggies. And seed is not more than 50% of their diet.
I made enough to fill 2-3 small bowls. Then froze it in little ice cubes. After freezing in ice cubes (cut in half, so two sections each cube) I put the cubes (or half cubes) in plastic, and glass containers in my deep freezer. So I don't have to make any more for months.