Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper for easier cleanup.
In a large bowl, toss the cauliflower florets with olive oil, salt, and pepper until evenly coated. Spread the cauliflower in a single layer on the prepared baking sheet.
Roast the cauliflower for 20-25 minutes, or until tender and nicely browned with crispy edges, flipping halfway through.
While the cauliflower is roasting, prepare the spicy peanut sauce. In a medium bowl, whisk together the peanut butter, soy sauce, rice vinegar, honey (or maple syrup), sriracha, minced garlic, and grated ginger.
Add hot water, one tablespoon at a time, whisking until the sauce reaches your desired consistency. It should be pourable but still thick enough to coat the cauliflower.
Once the cauliflower is roasted, remove it from the oven. Drizzle the spicy peanut sauce generously over the hot cauliflower directly on the baking sheet. Toss gently to coat all the florets.
Return the sauced cauliflower to the oven for another 5 minutes to allow the sauce to heat through and meld with the cauliflower.
Remove from the oven, garnish with chopped peanuts, fresh cilantro, sesame seeds, and serve immediately with lime wedges on the side.