In a small saucepan, cover the garlic cloves with 1½ cups of the olive oil and cook over low heat until the garlic is tender and golden brown, 35 to 40 minutes. Strain the garlic through a fine sieve set over a small bowl; reserve the garlicky olive oil for another use. In a small bowl, mash the garlic with 1½ tablespoons of salt and 1½ teaspoons of pepper. Rub 3 tablespoons of the garlic paste all over the flank steaks
2.In a medium bowl, whisk the lemon juice with the remaining ¾ cup of olive oil and the oregano. Place the steaks in a 9-by-13-inch baking dish and coat with 1½ cups of the lemony marinade. Let stand at room temperature for 1 hour.
3.Light a grill. Remove the steaks from the marinade, pat dry and season with salt and pepper. Discard the marinade. Grill the steaks over moderately high heat, turning once, until lightly charred and an instant-read thermometer inserted in the thickest part registers 125°, 8 to 10 minutes. Dip the grilled steaks in the remaining marinade in the bowl and transfer to a carving board. Spread the remaining garlic paste on the steaks and let stand for 5 minutes. Thinly slice the meat against the grain and serve.