Any vegetables would work in this recipe. Seasonal vegetables are best for your budget. So think about adding eggplant in late summer/early fall or sweet potatoes in late fall/early winter. Carrots are great at any time. Canned peas work well if you don't have canned French green beans. If you are adding different vegetables, just be conscious of cutting them to size. Carrots take a long time to cook if you cut them in large chunks, so you'll want to cut those small. Zucchini cooks quickly, so you'll want to cut that into large, diced pieces rather than thin rounds.