Combine wine, oil, garlic, 3 tablespoonsoregano, ancho chile powder, lemon juice,1 green onion, sugar, salt, and pepperin blender. Blend mixture until smooth.
Transfer marinade to 13 x 9 x 2-inch glassbaking dish.
Add lamb and turn to coatevenly. Cover dish tightly with plastic wrapand refrigerate overnight.
Prepare barbecue (medium heat). Grilllamb with some of marinade still clingingto surface until lamb is cooked to desireddoneness, 15 to 16 minutes per side formedium-rare (130°F).
Transfer lamb tocarving board.
Let lamb rest 15 minutes.
Meanwhile, finely chop remaininggreen onion and 1 tablespoon oreganoleaves; combine in small bowl.
Thinly slice lamb across grain. Arrangelamb slices on platter.
Pour over anyaccumulated juices.
Sprinkle with onion-oreganomixture and serve.
* Available in the spice section of manysupermarkets and at Latin markets.