• 1 L water (may be less for denser concentrate - used this much for simpler measuring)
• 10 Lipton Green Tea bags - cut the strings, boil in that water for 5 minutes
• 7 ml citric acid
• 8 ml potassium citrate (Ostrovit brand, 4.8 g)
• 2 ml vitamin C (1.2 g)
• 4 ml caffeine powder (1.2 g)
• 40 mg potassium sorbate (not strictly necessary if consumed early)
• 250g erythritol
• 75g xylitol

Makes 4 L of resulting drink, mix 1:3. Saturate with ~4 bar of CO2 after the mix has been cooled down to 4 C. Does not foam, concentrate should keep rather well due to antibacterial and antifungal contents. Relatively high caffeine content warning.

Yes, this is not mate, but it's chaicola. Will be mate when I get to steep mate.