On a cutting board, chop and reserve 1/4 cup fennel fronds. Trim the bulb(s), cut it in half and very thinly slice by hand or with a mandoline. Transfer to a large serving bowl and add the peppers, radicchio, lemon juice, a healthy douse of EVOO (eyeball it), the reserved fennel fronds and salt and pepper, to taste. Toss and let stand for 15 minutes, then toss again and serve.