SQL & PL/SQL :: Splitting One Row To Multiple?

I have a table Product as;
desc product
Name Null Type
--------------------------------------------------------------
PRODUCT_ID NOT NULL NUMBER
INGREDIENT VARCHAR2(20)

The data in Ingredient is separated by ','.
PRODUCT_ID INGREDIENT
---------------------- --------------------
1 A,B,C
2 A,D
3 E,F

I need to write a sql statement which will retrieve a pair of product and ingredient in each row as;

PRODUCT_ID INGREDIENT
---------------------- --------------------
1 A
1 B
1 B
2 A
2 D
3 E
3 F

write this sql ?