Season the chicken breast chunks generously with salt and pepper. Heat a skillet over medium-high heat and sear the chicken for 6-8 minutes, stirring occasionally, until golden brown on all sides and cooked through (internal temperature of 165°F). This creates flavorful caramelization that will make the bowl much more interesting than plain boiled chicken. Remove from heat and let cool slightly before assembling the bowl.
While the chicken cooks, slice the cucumber into 1/4-inch half-moons, halve the cherry tomatoes lengthwise, thinly slice the red onion into slivers, and measure out the kalamata olives. I find it helpful to prepare vegetables this way so they're ready to assemble and maintain their crisp texture rather than sitting in liquid.
In a large bowl, create a base with the cottage cheese. Arrange the cooked chicken from Step 1 and all prepped vegetables from Step 2 on top. Sprinkle the dried oregano and crumbled feta cheese over everything. Drizzle the Greek vinaigrette over the entire bowl just before serving—I add it at the last moment so the fresh vegetables stay crisp and don't get soggy.