Cook pasta in a large pot of salted boiling water per packet directions. Drain, then rinse briefly under cold water. Leave to cool. Transfer into large bowl.
Drain oil from the jar of sun dried tomatoes.
Measure out oil according to ingredients, top with extra virgin olive oil if short. Reserve excess oil for another purpose.
Add remaining Dressing ingredients. Mix well.
Add spinach, chicken, tomato, and onion, to large bowl with chicken. Pour over Dressing. Toss well, sprinkle with dried herbs, toss again.
Just before serving, sprinkle with crumbled feta. Best served at room temperature.