I don’t particularly like spicy foods, and I found expanding my vegetarian diet easier when I stopped trying to make complicated meals, especially those requiring buying lots of unique ingredients only used in one dish or requiring following long paragraphs of instructions. For most of history, people ate food in season and it was without a lot of weekly variety. If she has a list of foods she likes, even if its small, so long is as they include the spectrum of nutrients she needs, and she’s not leaning on sugar and fat, I would let her start by focusing on eating what she likes, not introducing lots of unfamiliar foods, even if that means she’s eating a week or more of the same type of dish (like baked potatoes or pizza.)
Something I learned growing up with my sister, who later it was discovered had certain dietary needs, is that the foods she strongly liked – acidic foods, sour foods and bitters – were actually foods she needed to balance out her personal chemistry. Sometimes kids’ natural tastebuds and “dislikes” are what their body is telling them is “good” and “bad” for them, personally.
Many 10 year olds of course are attracted to vegetarianism simply because they are animal lovers rather than because they dislike the typical family meal. But I was better off when I stopped thinking of how to make vegetarian meals look like what the meat-eating majority thinks counts as dinner. A plate of whole grain bread or crackers, a bit of cheese, raw veg, nuts and fruit is very often my dinner, and I probably wouldn’t eat healthily if I was faced with the challenge of shopping and prepping to make a vegetarian pad thai or gumbo.
Truly don’t mean to sound negative about recipes, and will offer the constructive idea of helping to introduce the 10-year-old to the very wide variety of legumes and whole grains on the planet and discovering which she likes best. There is a big difference in flavor between black beans, lentils and chickpeas or peas, or buckwheat or barley or brown rice, but they’re all good, and a 10 year old might find it fun to shop, soak and try out that wide variety. Hopefully the rest of the family, even if they are sticking to meat, will join in sampling some of these as side dishes too because a 10 year old will have a hard time eating up all the purchases by herself.
But unless the child is actually suffering some nutrient deficit because of her refusal to eat certain foods, variety in diet is just a preference for some, not nutritionally necessary. There are many cultures where children and families do not eat something different for dinner every night of the week, and even parents aren’t fond of unfamiliar foods. I’m all for introducing kids to the widest possible experience of eating, but if they settle on a limited diet, and reject some food after one bite, that’s not a flaw or something they should be taught to change.