1. In a small saucepan, combine the oil, garlic, sage, and 1/4 teaspoon each of the salt and pepper. Cook over low heat, stirring occasionally, until the garlic just starts to brown, 8 to 10 minutes. Don't let it brown thoroughly, or it will taste bitter. Strain the oil into a small bowl, reserving the cooked garlic.
2. Light the grill or heat the broiler. Brush some of the oil over the fish and then season with the remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Grill or broil the fish, basting with the oil, for 4 minutes. Turn and cook, basting with the oil, until just done, 3 to 4 minutes longer. You should have about 2 tablespoons of the flavored oil remaining.
3. To serve, drizzle the remaining oil over the fish. Top with the cooked garlic.
Fish Alternatives: Try another firm fish, such as mako shark, swordfish, or tuna steaks.
Variations: Mahimahi with Thyme Garlic Chips: Use 1 tablespoon dried thyme in place of the sage.
Mahimahi with Oregano Garlic Chips: Use 1 tablespoon dried oregano in place of the sage.
Wine Recommendation: Garlic invites refreshing sips between bites but can overwhelm many wines. Try an easy-drinking rosé or a white zinfandel from California.