Heat 1 1/2 teaspoons oil in a large heavy skillet over high heat. Add half of the peppers and 1/4 teaspoon crushed red pepper; saute until barely tender, 1 to 2 minutes. Add half of the squid and saute until opaque, 30 to 45 seconds. Add half of the lemon pieces and saute until the lemon is just heated through, 30 seconds longer. Transfer the squid mixture to a serving dish and keep warm.