How do I perform this function recursively?

# evenList = ['GAAGCTCG', 'AAATTT', 'CTCTAGGAC']
# oddList = ['CCTCGGGA', 'GGGCCC', 'GAGTACCTG']

def matchList(evenList, oddList, integ):
    indexElement = 0
    indexList = 0
    totalIndexSeq = []
    acceptableList = ['AT', 'TA', 'at', 'ta', 'GC', 'CG', 'gc', 'cg']

    for x in evenList:
        indexedSeq = ''

        for y in x:
            if y + oddList[indexList][indexElement] in acceptableList:
                indexedSeq += str(indexElement)
            else:
                indexedSeq += "+"
            indexElement += 1

        indexList += 1
        indexElement -= indexElement
        totalIndexSeq.append(indexedSeq)
    return totalIndexSeq
# This is what is returned:
# ['0+234+6+']
# ['0+234+6+', '++++++']
# ['0+234+6+', '++++++', '012++5678']