Based on the 2nd definition of "Brew" on Answers.com it appears as though "mixing various ingredients" to make a beverage can be defined as brewing.
1. To make (ale or beer) from malt and hops by infusion, boiling, and fermentation.
2. To make (a beverage) by boiling, steeping, or mixing various ingredients: brew tea.
3. To concoct; devise: brew a plot to overthrow the government.