I really like how Heidi (from 101 Cookbooks) described this frozen yogurt: "straight, bright white yogurt with the sweetness playing off the tang of the yogurt".
But still not the consistency I'm looking for--it was really thick and creamy whereas I like my frozen yogurt to be cold, icy and refreshing. I read somewhere that you can add milk to the mixture, maybe 1/4 to 1/2 cup. Or, someone else mentioned that the yogurt was strained for too long.
3 cups strained yogurt (see below) or Greek-style yogurt
2/3 cup (150g) sugar
1-2 t lemon juice (haven't tried, but read this will heighten the tartness)
To make 1 cup (240g) of strained yogurt, line a mesh strainer with 2-3 layers of cheese cloth, then scrape 16 ounces or 2 cups (480g) of plain whole-milk yogurt into the cheesecloth. Gather the ends and fold them over the yogurt, then refrigerate for at least 6 hours. (So, for the above recipe start with and strain 6 cups of yogurt.)
Mix together the yogurt, sugar, and vanilla (if using). Stir until the sugar is completely dissolved. Refrigerate 1-3 hours.
Freeze in your ice cream maker according to the manufacturer's instructions.
Makes about 1 quart, adapted from 101cookbooks.com