This recipe (from Martha Stewart via the Craigslist food forum) seems good:
Blood Orange Gelato

Makes about 1 quart

- 2 cups whole milk
- Zest of 1 blood orange, plus 1 cup freshly squeezed blood-orange juice (about 4 oranges)
- 5 large egg yolks
- 3/4 cup sugar
- 1 cup heavy cream

1. In a medium saucepan, combine milk and orange zest. Bring to a gentle boil, cover, and remove pan from heat. Let steep 30 minutes.

2. In a small saucepan, cook orange juice over medium-low heat until reduced by three-fourths, 30 to 40 minutes. Remove pan from heat, and let orange syrup cool completely.

3. Combine egg yolks and sugar in the bowl of an electric mixer fitted with the paddle attachment. Cream at medium-high speed until very thick and pale yellow, 3 to 5 minutes. Return milk to a simmer.

4. Add half of warm milk to egg-yolk mixture; whisk until blended. Return new mixture to saucepan. Cook over low heat, stirring constantly, until thick enough to coat back of a wooden spoon.

5. Have ready an ice-water bath. Remove saucepan from heat; immediately stir in cream. Pass mixture through a sieve set over a medium bowl. Place bowl in ice-water bath; chill. Stir in orange syrup.

6. Freeze in ice-cream maker according to manufacturer’s instructions. Store in an airtight plastic container up to 2 weeks.