Heat oven to 500°F. Drizzle the cut sides of the zucchini with 2 tablespoons of olive oil.
Bake on a rimmed baking sheet until charred and soft, 45 minutes. Remove from oven and cool.
Scoop out the flesh and combine with the tahini, lemon juice, and salt. Top with the crushed red pepper flakes, toasted sesame seeds, pepper, and remaining olive oil.