In a large pot over medium-high heat, heat 1 tablespoon oil. Sauté leek for 2–3 minutes, until softened. Add shrimp and garlic; cook for 2–6 minutes more, until shrimp is opaque. Remove to a dish; return pot to heat. Add
1 cup warm broth, millet, and sage. Bring to a boil, stir vigorously for 1 minute, and then reduce heat and cook until broth is almost absorbed. Continue adding warm broth, 1⁄2–3⁄4 cup at a time, stirring vigorously after each addition and waiting until broth is partly absorbed before adding more. Cover pot between additions.