Chickpea Feta Salad over Greens

3 tablespoons olive oil

1/2 teaspoon grated lemon zest, plus 3 tablespoons lemon juice 

Kosher salt and freshly ground black pepper

Kosher salt and freshly ground black pepper 

5 cups mixed greens (about 10 ounces) 

1 cup grape tomatoes, halved lengthwise 

One 15-ounce can chickpeas, drained 

2 kirby cucumbers, sliced into half-moons 

1 large shallot, chopped 

1/2 cup crumbled plain or herbed feta, crumbled