In a large zip-top bag, mix together the flour, paprika, garlic powder and some salt and pepper. Add the chicken and toss to coat completely.
In a large saucepan over medium heat, heat the oil. Add the chicken and brown on all sides, 3 to 4 minutes per side. While the chicken is cooking, to a slow cooker add the tomatoes, peppers and onions. Top with the chicken thighs.
In same skillet used to brown the chicken, add the tomato paste and cook for 1 minute, stirring constantly. Add the chicken broth and bring to a simmer, stirring to scrape any browned bits off the bottom of the pan. Pour over top of the chicken in the slow cooker. Cook on low for 4 hours, or until the chicken is extremely tender.
In a medium pot, combine 2 cups water, the rice, red pepper flakes, lemon zest, juice of half the lemon and a pinch of salt.
Bring to a boil, reduce to a simmer and cook, covered, until the rice is tender and has absorbed all the liquid.
To serve, spoon the rice onto a deep-sided platter and ladle the Spanish chicken and vegetables over top. Garnish with the olives and squeeze over the remaining lemon juice.