MISHNA BERURAH YOMI MISHNA BERURAH DIRSHU MAY 19

S"A SIMAN 202 M"B SIF KATAN 18
If you have a sour fruit make a shahakol on it unless it is cooked or sweetned by fire then it is fruit that being made edible for eating
Mishna Berurah Dirshu chelek 2
Q: What bracha do you make on cooked fruits and lemon

A:S"A sif 12 says when you cook a raw fruit that made to be cooked you make a shahkol on it m"b sik katan 64 adds even if it tastes good cooked
Rav Shilomo Zalman Aurbach says the bracha you make on a lemon is shahakol S"T Or Litzion adds if its really sour you dont make any beracha on it(for more see mishna berurah dirshu notes 17 18 and 19)