Polls.vue

<template>
<!-- ... html -->
          <SinglePoll
            v-for="poll in polls"
            @optionVote="handleOptionVote"
            :key="`poll-${poll.id}`"
            :poll="poll"
          />
<!-- ... more html -->
</template>

<script>
import { POLLS } from '@/gql/queries/poll.queries'
import { VOTE_ON_POLL } from '@/gql/mutations/poll.mutations'

import SinglePoll from '@/components/SinglePoll.vue'

export default {
  // ... code

  methods: {
    handleOptionVote(optionId) {
      this.$apollo.mutate({
        mutation: VOTE_ON_POLL,
        variables: {
          optionId
        }
      })
    }
  }
}
</script>