1. Enter the name and unit price of the dish in advance in sheet2 (this unit price can be modified at any time), as shown in the following figure
2. In sheet1, select column A, set the data validity, select the sequence, and set the source in sheet2! $A$2:$A$1111 (this 1111 depends on how many dishes you have). Set B2 formula to =IFERROR(VLOOKUP($A2,Sheet2! $A:$C,2,1), ""), C2 formula is =IFERROR(VLOOKUP($A2,Sheet2! $A:$C,3,1), ""), E2 formula is =IFERROR(C2*D2,1). Then pull down the B2 C2 E2 formula to fill it.
when you need to register in the future, you only need to select the name of the dish in column A, enter the quantity in column D, and the unit price amount will be automatically generated.