Roast the bell pepper quarters under the broiler.
Put the peeled feta cheese, cream cheese, peppers, mint, olive oil, garlic and juice of one lemon in a food processor form and whisk until the ingredients are well mixed, but some texture is still visible. If necessary, dilute with a little water. Season vigorously with salt and freshly ground pepper. Cover and refrigerate for at least 30 minutes to allow flavors to combine.
Serve chilled as a dip.
Cook up to 3 days in advance.