strong green tea; bitter green tea
Refers to green tea that is strongly astringent or bitter, often due to over-steeping or low-quality leaves. Not a negative term per se; some people enjoy the robust flavor.
The strong green tea at this shop has a pronounced bitterness and a mature flavor.
Compound of 渋 (しぶ, 'astringent, bitter') and 茶 (ちゃ, 'tea').