Combine oil and annatto (if desired) in a saucepan; cook over low heat 5 minutes. Remove from heat; let stand 10 minutes. Strain through a sieve over a bowl; discard seeds. Heat 1 1/2 teaspoons oil mixture in pan; discard remaining oil mixture. Add garlic; sauté 3 minutes. Add juices; bring to a simmer. Stir in tomato and remaining ingredients, and remove from heat. Serve warm over grilled fish or chicken.
Note: Salsa can be made up to two days ahead of time; cover and chill. Reheat in the microwave or in a saucepan over medium heat. If you choose not to use the annatto, use only 1 1/2 teaspoons oil.