1 Cook the orzo pasta: Bring to a pot of salted water to a rolling boil (1 Tbsp of salt for every 2 quarts of water). Add the orzo to the pot. Leave uncovered, cook on high heat with a vigorous boil for 8-10 minutes until al dente (cooked, but still a little firm).
Drain. Rinse with cold water to cool quickly.
2 Toast the pine nuts: Toast the pine nuts by heating a small skillet on medium heat. Add the pine nuts and stir occasionally until the pine nuts are lightly browned. Pay attention or you’ll burn the pine nuts.
3 Purée half the spinach with 1 Tbsp olive oil, mix with orzo: Take half of the spinach and purée it in a food processor or blender, adding one tablespoon of the olive oil. In a large serving bowl mix the spinach purée olive oil mixture in with cooked orzo until the pasta is well coated with the purée.
4 Mix onion, feta, pine nuts, olives, remaining spinach with the orzo: Roughly chop the other half of the spinach. Then gently mix the spinach, the red onion, feta cheese, pine nuts, and the Kalamata olives in with the orzo.
5 Make dressing: In a small jar, combine the remaining olive oil (2 Tbsp), balsamic vinegar, red wine vinegar, mustard, dried basil, and dried tarragon. Put a lid on the jar and shake to combine. (You can also just whisk together these ingredients in a small bowl, but the jar method works great to get a good emulsion.)
6 Pour dressing over orzo: Pour over orzo spinach mixture and gently mix in until well incorporated.