Oracle 21c

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CREATE TABLE t
    ("id" int, "content" varchar2(33), "previous" varchar2(4), "next" varchar2(4))
;
INSERT ALL 
    INTO t ("id", "content", "previous", "next")
         VALUES (1, 'Preheat an oven to 220 degrees C.', NULL, '2')
    INTO t ("id", "content", "previous", "next")
         VALUES (2, 'Peel potatoes.', '1', '4')
    INTO t ("id", "content", "previous", "next")
         VALUES (3, 'Toss sliced potatoes with oil.', '4', '6')
    INTO t ("id", "content", "previous", "next")
         VALUES (4, 'Cut potatoes into slices.', '2', '3')
    INTO t ("id", "content", "previous", "next")
         VALUES (5, 'Season the slices.', '6', NULL)
    INTO t ("id", "content", "previous", "next")
         VALUES (6, 'Bake in the oven for 30 minutes.', '3', '5')
SELECT * FROM dual
;
6 rows affected

select           "content"
from             t
start with       "previous" is null
connect by prior "next" = "id"


content


Preheat an oven to 220 degrees C.

Peel potatoes.

Cut potatoes into slices.

Toss sliced potatoes with oil.

Bake in the oven for 30 minutes.

Season the slices.