I think the most effective way to help your tortoise would be to dice up some cucumber with other types of food (cactus, spring mix, escarole, mulberry leaves, grape leaves, dandelion greens, mustard greens, and turnip greens just to name a few) also diced up. Start with a small amount of the other types of food and gradually increase their amount until your tortoise willingly eats the other type of food.
Dandelions
Grape leaves
Grass and weeds from your garden
Hibiscus -- flowers and leaves
Nasturtium
Roses -- flowers and young leaves
Squash -- banana squash, summer squash, and yellow crookneck squash
Succulents -- Aloe vera
Wandering jew
Zucchini fruit and leaves
Grass cuttings (if the grass is free of herbicides/pesticides and any of the other ides, as well as fertilizer free)
Feed other greens, they do not have a liking for spinach and seeds that size are not a good thing to feed. Use some of the other food suggestions and you can also try the dry foods like Mazuri. I think its more of a matter of just offering the right foods then it only wanting to eat the cucumber.