ha ha ...metric is English but I guess you're looking for imperial.
2/3 cup water
1 tsp fleur de sel (one heaped teaspoon)
scant 1 1/2 cup flour (it's just a little under so just don't pack it in)
1/2 butter, melted and cooled
for the détrempe, and:
1 1/2 cup butter
2/3 cup flour