Separately, cook the lentils and wild rice according to the package directions. Meanwhile, pour about 1/2 inch of water into a small saucepan and bring to a simmer over medium-high heat. Fit a steamer basket in pan. Place the spinach in steamer, cover, and steam until wilted, 1 to 2 minutes. Transfer to a plate. Spoon the warm rice and lentils over the steamed spinach. Top with the bell pepper, scallion, oil, and black pepper.