The specific steps for writing a complaint about the canteen of a nursing home are as follows:

1. Letterhead: Write your name, address, contact information and date, and the name of the nursing home that received the complaint letter. Name and address.

2. Introduction: State the purpose of writing the letter, and clarify the object of the complaint (nursing home canteen) and the time period.

3. Problem statement: Describe the complaint in detail, including the specific incident, time and location. Specific dissatisfaction or unreasonable matters can be listed, such as food quality, food taste, food type, food quantity, food hygiene, etc.

4. Attached evidence: Provide relevant photos, videos, purchase vouchers and other evidence to support the complaint.

5. Impact and feelings: Describe the impact of these problems on yourself or your family members you care about, such as loss of appetite, malnutrition, physical health problems, etc., and express your dissatisfaction and concerns.

6. Requirements and expectations: Clearly state your expectations and requirements, such as requesting to improve the food quality in the canteen, increase menu types, improve hygiene standards, etc. You can also suggest some improvement plans and suggestions.

7. Ending: Express your desire to get a solution and reply, and leave your contact information, such as phone number or email, so that the nursing home can contact you.

8. Signature: Write your name and leave enough space below for your signature.