I've been trying many things with cooking, but as yet have received only 1 Gastronomy points, for 7 Perch 7 Carrots 1 Duelling Serpents. As it seems many people reported getting gastro. using 7 Perch + 7 Carrots + "X", I simply tried many things until it "clicked." I had someone taste the masterpiece, for which he also received 1 gastro. point, and then had him try to make the recipe, hoping that perhaps masterpieces could be taught to others. This didn't work, and after long cooking stints using both methodical and "wild" approaches, I am pretty much convinced that Gastronomy points are random.
Recipes with Carp/Cabbage
4 Carp 4 Cabbage = 1 Str
4 Carp 3 Cabbage = 0
4 Carp 3 Cabbage 1 Chromis = 0
3 Carp 4 Cabbage = 1 Str 1 focus, 5 minutes
3 Carp 4 Cabbage 1 Mutton = 1 Str 1 focus, 3 minutes
3 Carp 4 Cabbage 4 Mutton = 0
3 Carp 4 Cabbage 1 Abdju = 1 Str 1 focus, 3 minutes
3 Carp 4 Cabbage 1 Sand Spore = 1 Str 1 Con , 7 minutes
3 Carp 4 Cabbage 3 Onions = 1 Str , 4 minutes
3 Carp 4 Cabbage 4 Leeks = 0
3 Carp 4 Cabbage 3 Carrots 4 Chromis = 0
6 Carp 8 Cabbage = 1 Str 1 focus, 3-5 minutes
6 Carp 8 Cabbage 7 Carrots = 0
6 Carp 8 Cabbage 1 Iron Knot = 1 Str 1 focus, 3-5 minutes