Tian Provençal — Layered Vegetable Gratin of Provence

Ingredients

• For the base
• 1 onion, sliced
• 3 cloves garlic, sliced
• 4 tbsp olive oil, for sweating
• 400 g passata or fresh tomatoes, cooked, seasoned tomato sauce
• For the vegetable layers
• 2 medium courgettes, sliced into uniform 4–5 mm rounds on a mandoline
• 2 medium aubergines, sliced into uniform 4–5 mm rounds on a mandoline; salted 30 minutes before use
• 4 ripe tomatoes, sliced into uniform 4–5 mm rounds
• 2 cloves garlic, thinly sliced, to scatter between rows
• For seasoning and finishing
• 80–100 ml finest olive oil, divided: most for drizzling before baking, a little reserved for finishing
• 1 tsp fleur de sel
• 1 tsp black pepper, freshly ground
• 4 sprigs fresh thyme, leaves stripped from stems
• 1 handful fresh basil, torn, for finishing
• 40 g breadcrumbs, toasted with garlic and Parmesan
• 20 g Parmesan, grated, for the toasted breadcrumbs

Method

1. 1
   Salt the aubergine rounds and leave them in a colander for 30 minutes. Pat thoroughly dry with kitchen paper. The slices should feel firmer and the paper should show drawn moisture.
2. 2
   Heat a film of olive oil in a wide pan over a medium flame. Add the sliced onion and cook until fully soft and translucent, then add the sliced garlic and cook a further two minutes. Add the tomato sauce, season, and simmer until the mixture is thick enough to hold its shape when spread. Spread this base evenly across the bottom of a large, shallow earthenware gratin dish. The base should coat every centimetre of the dish floor without pooling.
3. 3
   Heat the oven to 180 °C. Slice the courgettes and tomatoes into uniform 4–5 mm rounds, matching the thickness of the aubergine. Arrange the vegetable slices in alternating, overlapping rows directly onto the tomato base — one round of courgette, one of tomato, one of aubergine — repeating across the length of the dish. Each slice should sit upright at a gentle angle, leaning against the next, like fallen dominoes stood in sequence. Scatter the sliced garlic between the rows. This is where the dish lives or dies: uniform thickness and disciplined alternation are what ensure even cooking and the composed, architectural presentation that separates a tian from a stew.
4. 4
   Season generously with fleur de sel, black pepper, and the stripped thyme leaves. Drizzle the bulk of the olive oil — 80–100 ml in total, reserving a little for finishing — evenly over the surface. Every exposed edge should glisten.
5. 5
   Cover the dish loosely with foil and place in the oven for 40 minutes. At the end of this period, lift one edge of the foil: the vegetables should have softened and begun to yield, the base sauce should be gently bubbling at the edges, and the aroma should be warm, herbed, and sweet.
6. 6
   Remove the foil and return the dish to the oven for a further 25–30 minutes. The tian is ready when the exposed upper edges of the vegetable slices are crisp and lightly charred, the base is concentrated and jammy, and a knife pressed into the centre meets no resistance from any slice.
7. 7
   Remove from the oven and rest the tian for 10 minutes uncovered. Finish with a drizzle of raw olive oil, torn basil leaves, and a scattering of breadcrumbs toasted with garlic and Parmesan. Serve warm or at room temperature — never directly from the oven.