In a bowl, combine the chicken, 2 tablespoons olive oil, balsamic vinegar, paprika, oregano, shallots, garlic, lemon juice, lemon zest, crushed red pepper flakes, and a large pinch of salt. Marinate for 15 minutes or up to overnight in the fridge.Meanwhile, make the croutons. Heat the olive oil in a small skillet over medium heat. When the oil shimmers, add the bread and a pinch of red pepper flakes. Cook, stirring occasionally until golden and toasted all over, about 5 minutes. Remove from the heat and season with salt. Slide bread crumbs onto a plate. Wipe the skillet clean. Make the salad. Combine all ingredients in a large salad bowl, gently tossing to combine. To make the vinaigrette. Combine all ingredients in a glass jar or measuring cup and shake (or whisk) until completely smooth. Taste and adjust the salt and pepper. Thin the vinaigrette as needed with 2-3 tablespoons water. Heat the same skillet use for the croutons over medium high heat. Add the chicken in a single layer and cook, stirring once or twice, until the chicken is cooked through, about 5-10 minutes. To the salad, add the chicken, croutons, and drizzle with the vinaigrette. Gently toss to combine. Once the salad has been tossed, serve immediately,