Heat oven to 425°. Toss bread pieces with 1 tablespoon olive oil. Season with salt and pepper. Spread evenly on a baking sheet and bake until golden, about 8 minutes, tossing once. Let cool.Scrub beets and wrap in aluminum foil. Place in a baking pan and bake until tender, about 1 hour. Let cool slightly.While beets are roasting, zest oranges and set zest aside. Use a sharp knife to remove peel and white pith from oranges. Working over a large bowl, cut between membranes to release segments. Place segments aside and squeeze membranes over bowl to release juices.Whisk remaining 3 tablespoons oil, vinegar, maple syrup, garlic, and 1 teaspoon reserved orange zest into bowl with orange juice. Season with salt and pepper. Add kale and lightly massage kale to coat with dressing. Add orange segments and onion.Use a paper towel to peel skins off slightly cooled beets. Cut into quarters. Add beets to bowl with kale. Toss lightly. Add toasted bread and toss to combine. Season with salt and pepper. Let rest 30 minutes before serving garnished with additional orange zest.