For the soup: Heat the EVOO in a soup pot over medium heat. Add the onions and garlic. Season with salt and pepper and cook until tender, 8 to 10 minutes. Add the stock and peas, bring to a boil, then reduce heat to a simmer and cook until just tender, 20 minutes. Remove half the soup and puree with the mint and parsley until smooth in a food processor or high powered blender. Return the puree to the pot, and stir in the lemon juice. Taste and adjust the salt and pepper. Cool and store for a make-ahead meal.
For the flatbread: Arrange the flatbread on a wire rack over a baking sheet, spray with the olive oil on both sides and season with salt and oregano. Roast in the oven to toasted and crisp. Store at room temperature in an airtight container.
Reheat the soup over medium heat. Serve the soup garnished with feta crumbles and a light sprinkle of cumin and paprika, a drizzle of EVOO and flatbread chips.