Serve some of what you are cooking
If the family is eating rice, soup, or a soft vegetable, their plate can hold a piece of that same meal.
They can join the table
Keep one food they already accept next to the family food. They are joining the table, not sitting through a test.
Take their portion out before a hot chilli, a salty sauce, or a food that clashes with an allergy. The family pot can still be the starting point.
Soup, rice, and soft vegetables
A ladle of the vegetable soup, with the pieces soft, plus the rice they already eat, is a shared dinner.
Very hot food waits. Lukewarm is the comfortable version for a toddler.
One pot, different plates
A vegetarian child can eat the rice and vegetables from a meal that also has meat for someone else. Serve their plate from the parts that fit.
Chicken stays off when the diet does not include meat. Egg stays off when the diet is vegetarian or egg is an allergy.
A sentence you can say
“This is some of our soup, and your rice.”