Leave the new food on the plate
If they ignore the new food, leave it there until the meal ends. Taking it away the second they frown teaches them that a frown clears the plate.
Presence is the offer
You also do not have to talk about it. The food can simply be present.
A frown, a poke, or a look away can all happen while the food stays. The meal ends when they are done, not when the new food disappears.
When to actually remove it
Take it away if they are throwing it, or if the meal has tipped into distress. Those are different from ignoring it.
If distress is becoming the pattern, talk to your child’s doctor. A daily fight is more than a food you should push through.
What you say instead of a sales talk
Name the familiar food. Mention the new food once if you want. Then talk about the day.
“Just one bite” as the price of leaving the table turns the meal into a bargain. Skip that bargain.
A sentence you can say
“Your rice is here. The sweet potato can stay.”