Heat a large pot to medium high. Add a glug of olive oil. Slice a lemon in half and cook cut side down to brown. Add garlic, onion, herbs and cook for 3 - 4 minutes. Deglaze with wine. Add about a quart of water and a pinch of kosher salt. Bring to a boil. Lower the octopus into the boiling water and reduce heat to low.
Rinse the octopus under cold running water, then drain it and blot dry with paper towels. Step 2: Set up the grill for direct grilling and preheat to high. Step 3: When ready to cook, brush and oil the grill grate.
Let the octopus marinate for at least 5 minutes, or up to 30 (the octopus can be served warm or at room temperature). Taste for seasoning, adding more salt or wine vinegar as necessary; the octopus should be highly seasoned. Serve the octopus accompanied by lemon wedges.
You can let it sit in the fridge overnight or even freeze it for up to 1 month. While the octopus was resting at room temperature, I drizzled some olive oil over it and added some chopped garlic, so it can get some seasoning, before grilling. I cut its tentacles and grilled it over medium-high heat for 3-4 minutes per side.