Used crochet hook size G and Lion Brand Kitchen cotton. Other worsted cotton yarns also work.
Foundation: Ch 5, Join with slip stich to 5th ch from hook to make ring
Row 2: Ch 2, 14 hdc into ring, join with slip stich into 1st hdc of this row
Row 3: *ch 4, skip 1 hdc, slip stitch into next hdc* repeat 6 more times
Row 4: Ch 1 * 3 sc into next 4ch loop chain 1* repeat 6 more time, join with slip stitch into 1st ch of this row
Row 5: Turn work, slip stitch into 1st ch1 space, ch3, 4dc into same ch1 space * 5dc in next ch1 space* repeat 6
times, join with slip stitch at top of beginning ch3
Row 6: ch1, * sc in next 4 stitches, 2 sc in next stitch * repeat 6 more times, join with slip stitch
(note, row 7 is the triangular edging. It is worked by chaining 3 then working down that chain until triangle is made, then turn the triangle so that it attached to the coaster edge. The edging works counter clockwise around the coaster edge)
Row 7: * ch3, sc in 2nd ch from hook, dc in next ch (triangle made) turn triangle and join with ss in 3rd stitch from ch3 on coaster * repeat 13 more times. Join with slip stitch.
Finish off: hide ends. Skip blocking, after a couple cups of tea they stay flattened out