In a large pot, combine water, halved onion, smashed garlic, black peppercorns, kosher salt, lemon juice, parsley stems, and bay leaves. Bring to a boil, then reduce heat and gently add baby octopus. Simmer on low for 60 minutes, checking for tenderness after 45 minutes.

Once the octopus is tender, carefully pour it into a colander to drain. Discard aromatics from the pot and transfer cooked octopus to a large bowl.

In a mixing bowl, mix together extra virgin olive oil, minced garlic, lemon zest, and optional red chilli flakes. Pour over warm octopus and gently toss to coat. Let cool, then cover and refrigerate for 12 to 24 hours.

Heat a BBQ grill or skillet over medium-high heat and add canola oil. Once shimmering, carefully place marinated octopus in the pan. Sear for about 4 to 5 minutes until legs are crispy and golden-brown.

Transfer the crispy octopus to a serving platter. Drizzle with fresh lemon juice and garnish with parsley and sliced fresh chilli. Serve with lemon wedges.