Monaco is very picky, and hesitant to even taste a new food unless I eat it in front of her. Even then it can take a week or more of offering for her to eat some from her bowl. My chickens have been eating VERY well since she got here! It can be difficult and time consuming to find foods they'll eat, but so worth it!
Keep in mind that any new thing can really be stressful for them. This is why I eat in front of her. She's genuinely interested in sharing food, and she doesn't seem stressed or scared unless she gets frustrated that she doesn't want anything from my plate. When I put the new food in her breakfast bowl it's a small amount right next to something she likes... This goes on until she eats it or I run out, and then I start again with something else. I circle back to those untouched things occasionally, and sometimes she'll surprise me and eat it right away. Right now it's frozen Bing cherries. I thought I was going to have to make a pie, but she suddenly leaves all of her grapes and the cherries disappear quickly. It's been about 10 days of cherries and strawberries...oddly enough she has refused the strawberries the whole time and they're usually a favorite. They're really good, so it's confusing for me, but on we go. Sweet potatoes are up next, guava, and two of her staples: peas and corn to be sure she's eating enough. The whole process has been hard for me, because I'm a planner. Shop, prepare a lot, freeze, serve, no worries or interruptions...nice routine. So, she's teaching me patience and perseverance. But it's a lot of fun, too, sharing meals is one of my favorite things to do with her!
Start small, and don't give up! It's also not expensive if you get things you can freeze or eat yourself to prevent waste. I didn't think she would like lettuce, but she runs over to have at least a bite every time I have a salad! Surprise!