Splitting a column into two before and after the first appearance of a delimiter "/"

I have the attached dataframe.

DATA

structure(list(associated_gene = c(NA, NA, "A4GALT", NA, NA, 
   "NOT FOUND"), chr_name = c("22", "22", "22", "22", "22", "NOT FOUND"
   ), chrom_start = c(42693910L, 42693843L, 42693321L, 42693665L, 
   42693653L, 0L), allele = c("G/A/T", "T/C", "G/C", "C/T", "G/A/T", 
   "NOT FOUND"), refsnp_id = c("rs778598915", "rs11541159", "rs397514502", 
   "rs762949801", "rs776304817", "NOT FOUND")), row.names = c("s3a", 
   "s3b", "s3c", "s3d", "s3e", "s3f"), class = "data.frame")

    associated_gene  chr_name chrom_start    allele   refsnp_id
s3a            <NA>        22    42693910     G/A/T rs778598915
s3b            <NA>        22    42693843       T/C  rs11541159
s3c          A4GALT        22    42693321       G/C rs397514502
s3d            <NA>        22    42693665       C/T rs762949801
s3e            <NA>        22    42693653     G/A/T rs776304817
s3f       NOT FOUND NOT FOUND           0 NOT FOUND   NOT FOUND

I would like to split the allele column by the first "/" into two (Ref & Var) and insert them between $chrom_start and $refsnp_id

The ideal output is:

     associated_gene  chr_name chrom_start   Ref   Var   refsnp_id
s3a            <NA>         22    42693910     G   A/T rs778598915
s3b            <NA>         22    42693843     T     C  rs11541159

I dont know if I can load awk, but in bash I'd do:

cat allele | awk -F"/"'{print $1 "\t" $2}'