My first suggestion, Coconut Pellets! I don't care where you get them from but they make seed-starting "oh so easy." Before you just go crazy and start planting all of the seeds it's important to decide which varieties you would like to include and how long each will take to mature.
Not everyone likes onions in their salsa. I do! I prefer a red onion. The Red Burgundy onion matures in approximately 100 days. If you decide to grow this onion it should be planted first. If you choose a bunching onion or a "green onion" you can wait on planting. Bunching onion varieties take about 40-60 days to mature.
I prefer to use a smaller tomato for salsa like the Ace 55 or Roma. A larger option is a Brandywine. Both varieties take approx 75-80 days to mature so they should be started one month after the onion (if you chose the red). For fancy salsa, try Emerald Green or Amana's Orange tomatoes
For a mild salsa you can use Anaheim instead. For a hot (or hotter) salsa I use Jalapenos. For the crazy, burn you mouth for a week salsa, use Serrano Peppers! These pepper varieties also take 70-80 days to mature and should be planted at the same time as the tomatoes.
Cilantro planting should be staggered throughout the year. By planting multiple cilantro plants it will allow you to harvest as you need it instead of all at once. Plant Cilantro at least 30 days before the rest of the Salsa Garden plants mature. I recommend planting another crop the following week.
Onions: 100 or 40 days
Tomatoes: 75-80 days
Peppers: 70-80 days
Cilantro: 30 days
5 large tomatoes, chopped
1 onion, chopped
1/2 cup chopped fresh cilantro
3 cloves garlic, minced (optional)
1 tablespoon lime juice
1 tomatillo, diced (optional)
1 jalapeno pepper, minced
In a medium-size mixing bowl, combine tomatoes, onion, cilantro, garlic, lime juice, tomatillo, and salt to taste. Mix well. Add 1/2 of the jalapeno pepper, and taste. If you desire your salsa with more of a kick, add the remaining 1/2 jalapeno. If you are satisfied with the salsa's heat, do not add the remaining jalapeno pepper. Cover the salsa, and chill until ready to serve.