SELECT `o`.`title`, `f`.`value` AS `filling`, `t`.`value` AS `taste`
FROM `orders` AS `o`
LEFT JOIN (
SELECT `of`.`id_order` AS `id_order`, `of`.`value` AS `value`
FROM `order_fields` AS `of`
JOIN `fields` AS `f` ON `f`.`name` = 'Начинка' AND `f`.`id` = `of`.`id_field`
) AS `f` ON `f`.`id_order` = `o`.`id`
LEFT JOIN (
SELECT `of`.`id_order` AS `id_order`, `of`.`value` AS `value`
FROM `order_fields` AS `of`
JOIN `fields` AS `f` ON `f`.`name` = 'Вкус' AND `f`.`id` = `of`.`id_field`
) AS `t` ON `t`.`id_order` = `o`.`id`