Step 1Heat the oven to 425 degrees.
Step 2Peel the carrots and cut into one-half-inch-thick pieces. Toss with just enough olive oil to lightly coat, along with the cumin seeds, a generous one-fourth teaspoon salt and one-fourth teaspoon pepper, or to taste.
Step 3Spread the carrots onto a rimmed baking sheet and roast until the carrots are tender and golden brown, about 30 minutes, tossing occasionally for even coloring. Remove from heat and cool.
Step 4Place the cooled carrots in a large bowl and toss with the lemon juice and cilantro. Peel, seed and dice the avocado and toss with the carrots. Taste and adjust the seasonings and flavorings as desired. Chill completely before serving.