Use mature leaves, the young leaves all you get is chlorophyll, and make sure there has been no cats spraying the bushes??
Use about 2 Tsp chopped leaves to a cup, steap for a few minutes, it's not a strong tea and it's more for ailments, or you can dry some of the berries and use 1 tsp of berries in 1 cup of water in a pot, bring to a boil then turn off heat, let soak for about 25 min
put 2 tsp chopped leaves, soak another 5 min
strain add sugar or honey to taste.
Drinking black currant tea may be helpful in treating and preventing several diseases and conditions including cardiovascular disease, diarrhea, dysentery, cancer, allergies, and asthma. The leaves of the black currant bush may be beneficial for people suffering from kidney disorders due to their diuretic properties. You can also blend with black tea.