Fill a clean half-gallon glass jar (mason jar, pitcher, whatever you've got) with cold filtered water.
Add the tea bags. Let the tags hang over the rim if you can; it makes fishing them out easier later.
Set the jar in direct sunlight. A sunny windowsill works, but outside on a patio or porch is better.
Steep 2 to 3 hours. If you forget and it goes 4, no harm done. Just don't leave it out all day.
Bring the jar inside. Remove and discard the tea bags. Refrigerate until cold.
While the tea is brewing or cooling, make the symple syrup
Put the sugar and water into a small pot and bring to a rapid boil for 5 mins
Allow the syrup to cool and then strain into a jar and keep it in the fridge.
Pour the tea over ice. Add lemon, simple syrup, or mint if you want. Or don't.